The commonly used methods in scientific research are _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
_ _ _ _ _ is one of the most basic substances needed by living things and an important part of living things.
Generally speaking, the temperature of an object when it absorbs heat will be _ _ _ _ _ _ _ _, and the temperature when it releases heat will be _ _ _ _ _ _ _.
Why is water a thermostat? ________________________________________________
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_ _ _% of the earth's surface is covered by sea water. The vast ocean is like a huge _ _ _ _ _ _ _ _ _ _ system.
The four centers of ancient civilizations in human history are all located near the water: Babylon-_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
There is a lot of water on the earth, but there is not much water for human production and life. At present, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ This part of fresh water is what we usually call water resources available to human beings, accounting for only about _ _ _ _ _ of the total water resources of the earth. Freshwater mainly exists on the earth in the form of _ _ _ _ _ _ _ and _ _ _ _ _ _ _. There are _ _ _ _ _ _ kinds of differences and _ _ _ _ kinds of changes in the distribution of water.
China's per capita water resources are only _ _ _ _ _ _ _ _ of the world level, and the distribution is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
_ _ _ _ _ _ _ _ _ _ _ characteristics; The distribution of water resources in the world is characterized by _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
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Scientifically, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
The definition of quality is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
In the international system of units, the unit of mass is _ _ _ _ _. The unit of length is _ _ _ _ _ _, abbreviated as _ _ _ _.
1 kg = _ _ _ _ _ g, 1 ton = _ _ _ _ _ kg, 1 cubic meter = _ _ _ _ cubic centimeter. 1l = _ _ _ _ _ cubic centimeter.
The definition of density is: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. The density of water is _ _ _ _ _. The unit of density is _ _ _ _ _ or _ _ _ _ _,1g/cm3 = _ _ _ _ _ kg/m3.
Green plants absorb _ _ _ _ _ _ _ substances in soil and air, and synthesize _ _ _ _ _ _ _ _ _ _ _ _ elements.
We call an object that can emit light by itself _ _ _ _ _ _ _ _. The sun is the most important _ _ _ _ _ in nature. Solar energy mainly radiates to the earth in the form of _ _ _ _ _ _ and _ _ _ _ _. Dark objects can absorb more solar energy than light objects.
After a beam of sunlight passes through a prism, it can be divided into a colored light band, which is a _ _ _ _ _ _ phenomenon of light. We can see the _ _ _ _ _ _ phenomenon of light in the mirror and the _ _ _ _ _ _ phenomenon of chopsticks bending in water.
We can see a luminous object because the light it emits enters our eyes; We can see an object that doesn't emit light because it shoots light into our eyes.
The object reflects the colored light of its own color _ _ _ _ _ _ _ _, and absorbs the colored light of its own color _ _ _ _ _ _ _.
The three primary colors of light are _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Explanation: reflection _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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Refraction: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
In the same substance, light travels along _ _ _ _ _. Use a straight line with an arrow to represent _ _ _ _ _ _ and _ _ _ _ of light. This straight line is called _ _ _ _ _. The intersection of incident light and the interface is called _ _ _ _ _ _ _ _. A normal is an interface made of _ _ _ _ _.
The light path is reversible. The law of light reflection is: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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Draw a schematic diagram of light reflection on the right.
The law of flat mirror imaging is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
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Atmospheric pressure acts on objects, such as balloons floating in the air, from the direction of _ _ _ _ _ _ _ _ _, and is subjected to atmospheric pressure from all directions.
The volume percentages of various gases in the air are: oxygen: _ _ _ _ _ _ _ _ _; Nitrogen: _ _ _ _ _ _ _; Rare gas: _ _ _ _ _ _ _; Carbon dioxide: _ _ _ _ _ _ _; Other gases and impurities: _ _ _ _ _ _.
Oxygen can help substances burn; Nitrogen is the main element of protein; Rare gases are very stable, including helium, neon, argon, krypton, xenon and radon. In the air near the ground, the contents of nitrogen, oxygen and rare gases are basically the same everywhere, and they are stable components in the air. Carbon dioxide, water vapor and ozone are unstable components in the air.
Generally, an object will become larger when heated and smaller when cooled. This attribute is called _ _ _ _ _ _ _. In the horizontal direction, the air in the high-pressure area flows to the low-pressure area. (Look at the atmospheric circulation)
The air on the earth is distributed in _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ and _ _ _ _ _ _ _. Within 8 kilometers from the ground, _ _ _ _ _ _ of the total air mass is concentrated.
Soil is composed of _ _ _ _ _ _ _ elements.
According to the contents of _ _ _ _ _ _ _ and _ _ _ _ _ in soil, soil can be divided into three types: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Why are rice planted in paddy fields and peanuts planted in sand? ________________________________________
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Soil provides _ _ _ _ _ _ _ _ _ _ _ nutrients for plants.
_ _ _ _ _ _ _ Fleet completed the first round-the-world voyage in human history, and proved that the earth is round with facts.
The earth is an irregular sphere composed of _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Surface morphology can be divided into five types: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. The seabed topography is divided into _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ and _ _ _ _ _ _ _ _
Usually we call _ _ _ _ _ _ _ _ _ _ _ _ and _ _ _ _ _ _ as mountainous areas. The mountainous area of China accounts for about 15% of the total land area. The advantages and disadvantages of mountainous areas are _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
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Solar energy and gravitational energy belong to the external force of the earth. Under the action of external force, the surface morphology has been changing. (erosion, erosion, deposition, weathering, wind erosion, accumulation, etc.). )
A globe is a regular sphere that simulates the shape of the earth. Turn the globe from left to right. The axis around which the globe rotates is called _ _ _ _ _ _ _. The two intersections of the earth's axis and the earth's surface are _ _ _ _ _ _ _ and _ _ _ _ _ _. The arc connecting the two poles is _ _ _ _ _ _ _, also called _ _ _ _ _ _. Internationally, the meridian passing through the former site of Greenwich Observatory in London, England is defined as _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. It is customary to call the hemisphere from _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ as the Eastern Hemisphere and the other hemisphere as the Western Hemisphere. China lies in the Eastern Hemisphere.
The largest latitude circle on the earth is _ _ _ _ _ _ _ _, which divides the earth into two hemispheres. _ _ _ _ _ _ _ _ _ is a low latitude; _ _ _ _ _ _ _ _ _ _ is the middle latitude; _ _ _ _ _ _ _ _ _ is a high latitude.
The function of the latitude and longitude net is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
When using a map, you should first know _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. There are three ways to express the scale: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Altitude refers to the _ _ _ _ _ height above the average sea level. Generally speaking, the elevation difference between two adjacent contours on the same contour topographic map is _ _ _ _ _ _ _ _, and the gradient of the places with dense contours is _ _ _ _ _ _; Where the contour lines are sparse, the slope is _ _ _ _ _ _. Valley is where contour lines protrude to high altitude, and ridge is where contour lines protrude to low altitude.
The sun is made up of _ _ _ _ _. It takes more than _ _ _ _ minutes for sunlight to reach the earth.
The most important solar activities are _ _ _ _ _ _ and _ _ _ _. Sunspots are areas with low temperature on the surface of the sun, and flares are areas where the surface of the sun suddenly brightens. _ _ _ _ _ _ is the main sign of solar activity. The cycle is _ _ _ _ _ _ _ years. The surface temperature of the sun is about _ _ _ _ _ _. The temperature of sunspots is around _ _ _ _ _ _ _ _ _, which is relatively dark under a bright background.
The impact of solar activity on the earth is: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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The quality of the object is _ _ _ _ _ everywhere; The earth in distance to the moon is about _ _ _ _ _ kilometers, and the gravity on the moon is about _ _ _ _ _ of the earth; There is no air on the moon, so air-related activities cannot be carried out on the moon.
The solar system is composed of _ _ _ _ _ _ _ _ _ _ _ _ and _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ The mass of Jupiter is 2.5 times that of the other eight planets combined. _ _ _ _ _ is closest to the sun; _ _ _ _ _ _ is the brightest. See it at dawn, call it _ _ _ _ _ _ _, and see it after dusk, call it _ _ _ _ _ _ _ _ _; _ _ _ _ _ _ is farthest from the sun. The pianist discovered Neptune. Neptune was originally calculated by theory.
The meteor phenomenon is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Comets are generally composed of _ _ _ _ _ _ and _ _ _ _. Comets orbiting the sun in elliptical orbits are periodic comets; Aperiodic comets can only visit the solar system once.
People on the earth to see the sun running in the sky for one year route is called _ _ _ _ _ _ _ _.
You can see Pegasus in the southern sky and Cassiopeia in the northern sky in the autumn night. _ _ _ _ _ _ _ _ _ _ and _ _ _ _ are the signs of the autumn starry sky. The constellation in the sky in summer is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Wenquxing is the four stars of the Big Dipper.
As the earth rotates from west to east, people can see the phenomenon that the stars rise in the east and set in the west, which is called _ _ _ _ _ _ _ _ _ _ _ _.
Trees have _ _ _ _ _ _ _ _ _ _ _ _; The leaves are planted in _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _; The vein is _ _ _ _ _ _ _ _ _ _ _ _; The flower structure includes _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ The flowers of Chinese cabbage and rape are cruciform.
Woody plants with tall plants and obvious upright trunks are called _ _ _ _ _ _ _ _; Woody plants with no obvious trunk are called _ _ _ _ _ _ _, such as oleander (whose leaves are planted in rotation); _ _ _ _ _ _ The stems of plants are usually soft.
Eichhornia crassipes, also known as water hyacinth, has strong reproductive ability. Manjianghong is a kind of fern; Lotus stems are hollow, and it is easy to transport oxygen.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ and _ _ _ _ _ are the most important food crops in the world. In addition, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ and so on. It is also a very important food crop. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
The lotus root and potato we eat are _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Edible vegetable oil comes from rape, peanut, soybean, sesame and other crops; Cotton cloth is made of wool outside cotton seeds; Mountain tea can be made into tea; The fruits in Central China are citrus, peach, plum and apricot.
Metasequoia glyptostroboides was first discovered in Hubei on 1946. It's called _ _ _ _ _ _ _. There are natural factors and human factors that cause plants to be endangered.
What is the impact on animals after habitat destruction? ___________________________________________
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Leech is commonly known as leech, cicada is called cicada, slug is called slug, and toad is called toad.
The name of the Northeast Tiger is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Vision is highly degraded and hearing is specialized. Sonar system is mainly used to detect and identify objects, avoid enemies and prey on fish. The national first-class protected animals distributed in the middle and lower reaches of the Yangtze River are _ _ _ _ _ _ _ _.
Most plants and animals are developed from a small fertilized egg. Testicles produce sperm and ovaries produce eggs. The fertilization site is the upper end of the fallopian tube.
The fertilized egg divides to form an early embryo and is implanted into the uterus. The fetus is connected with the mother's uterus through _ _ _ _ _. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Identical twins have the same sex and similar appearance; Fraternal twins can be of different genders, but they generally don't look alike.
The difference between male and female reproductive organs is called primary sexual characteristics; In adolescence, with the development and maturity of reproductive organs, other physiological differences are manifested as secondary sexual characteristics. Sexual development in adolescence is regulated by sex hormones. Nocturnal emission and menstruation are normal physiological phenomena.
The main substances that make up the human body are water, protein, lipids, sugars and inorganic salts. Water is an important part of organism, which participates in the absorption of nutrients and the elimination of metabolic wastes. Water is also a medium for transporting substances in the body. Protein is the basic substance of organisms, which is indispensable for the renewal and repair of tissues and cells. Cell membranes of animals and plants are mainly composed of lipids. Sugar is an important part of DNA molecules. Inorganic salts in human body mainly include phosphorus, sulfur and calcium. Calcium is an important component in the formation of animal bones and teeth.
1 g water temperature rises 1 degree Celsius, which needs to be absorbed by _ _ _ _ _ _. The energy needed by the human body is mainly provided by _ _ _ _ _. If you eat too much nutrients, it will be converted into fat in the body, making people fat. In sugar, fat and protein, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
The six nutrients are _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. The seventh nutrient is cellulose, which can't be digested and absorbed by human body, but it is useful.
The main function of vitamins. (See the table on page 152)
Reasonable diet: there are various foods, mainly grains; Ensure the intake of fish, meat, eggs, milk, beans and vegetables, and eat less fat and meat oil; Diet and physical activity should be balanced, and proper weight should be maintained. The ratio of heat energy for breakfast, lunch and dinner is 3: 4: 3.
The main toxic substances in smoke are nicotine, tar and carbon monoxide. Long-term smoking can easily lead to lung cancer and other respiratory diseases. Cigarettes are called legal drugs.
The main component of wine is alcohol, and its chemical name is _ _ _ _ _ _ _ _. When the blood alcohol concentration reaches 0. 1%, the self-control ability is lost.
Infectious diseases are caused by viruses, bacteria, parasites and other pathogens, and can spread between people or between people and animals. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Influenza is caused by influenza virus, which can recover by itself in a week or so, but if children are not treated in time, they will be complicated with pneumonia, myocarditis and other diseases. Hepatitis B is caused by hepatitis B virus; The route of transmission of hepatitis B is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Foods and substances that are easy to cause food poisoning mainly include _ _ _ _ _ _ _ _ _ _ _ _ _ _.
Prevention of food poisoning: P 163.
The harm of electric current to human body is related to _ _ _ _ _ _ _ _ _ _ _ _ _ _ and other factors. When an electric shock accident occurs, you should _ _ _ _ _ quickly. When dealing with people who get an electric shock, we should pay attention to keeping them warm on their back, giving artificial respiration when necessary, and sending them to hospital in severe cases.
After being bitten by a poisonous snake, he was bound at a position about 5cm- 10cm near his heart.
Review the main points of each chapter in science class.
First of all, the world of water
1, is the largest water body on the earth, and the continent with the largest proportion of fresh water resources in the total water volume on the earth is
One of the objective reasons for water shortage in some places is that fresh water resources are on the earth.
3, China's water resources, however.
Water is an important substance for life on the earth. It plays an important role in nature.
At standard atmospheric pressure, the freezing point and boiling point of water are zero, and the density of water is the largest, which is why ice can float on the water in winter. Water resources are an important factor affecting economic development and play an important role in industry and agriculture. If there is no water on the earth, living things will not survive.
Second, sunlight, air and soil.
6. Objects that can emit light are called light sources. We can see a luminous object because its light enters our eyes. We can see things that don't shine because they enter our eyes.
7. Light propagates in the same homogeneous substance. The properties of light when it is reflected on the surface of an object.
8. White light is polychromatic and can be refracted through a prism.
Seven colors, life and mirage all belong to dispersion phenomenon.
9, pinhole imaging, solar eclipse and can prove that light travels along a straight line; The pencil bends in the water, and the fish in the water looks like real fish because of the light;
10, the sun is far away from the earth and provides energy for the earth. Energy is the source of the whole biological world and affects the activities and behaviors of living things.
1 1. There is an atmosphere around the earth with a thickness of 2000 km-3000 km, which can reduce the impact of meteoroids on the earth. The atmospheric pressure it forms acts on the object, forming the horizontal movement of air. Nitrogen in the air accounts for 4/5 of the total volume, oxygen is about 0, and it also contains inert gases, carbon dioxide and water, which are all greenhouse gases.
12. Soil is composed of minerals, organic matter, water and air. Organic matter determines soil fertility, and soil and plants are interdependent. Soil provides nutrients and water for plants, and the decay of plant residues in soil can make the soil more fertile.
Third, our home-the earth.
13, the ancients thought that "the sky is round", but it turns out that "the earth is round" was the Spanish navigator Magellan and his fleet, which is why we saw the mast of an ocean-going ship for the first time, standing high and looking far. In fact, the equatorial radius of the earth is slightly larger than the polar radius, and the earth is an irregular sphere with slightly flat poles and slightly bulging equator. The inertial centrifugal force generated by the earth's rotation flattens it, so we lean against it on the map. The longest latitude is the equator. We divide 200 W- 1600 E into the eastern hemisphere to avoid artificially dividing multiple countries. When using a map, be sure to pay attention to the direction, scale, legend and notes.
14. The most common landforms are plateaus, plains, mountains, hills and basins. The reason why the surface morphology is constantly changing is that in the contour lines under the action of wind, running water, glaciers, waves and other external forces, ridges protrude from high to low, valleys protrude from low to high, and the intersection of multiple contour lines is a steep cliff.
Fourth, look at the starry sky.
15, solar activity has a great impact on the earth and human beings, mainly including sunspots (low temperature) and flares (high temperature), among which sunspots are the signs of solar activity, and there is a cycle every 1 1 year, which easily interferes with communication and human health.
16, the moon is the natural satellite of the earth, and the gravity on the moon is only16 of that of the earth. There is a great temperature difference on the moon, so there is no water and no atmosphere, so the sound cannot spread, and meteoroids collide to form numerous craters.
17. In addition to the sun, the solar system also includes Mercury, Venus (the brightest is called Venus or the Pleiades), Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto [Golden Globe Award, Chai Earth, Tianhai Ghost], asteroids, meteoroids, comets, etc. Among them, Jin Mu is visible to the naked eye and discovered by the pianist.
Verb (abbreviation for verb) plant kingdom
18. Forests provide abundant resources such as food, medicine and industrial raw materials, and play an important role in soil and water conservation, climate regulation and air purification. Due to the difference of temperature and humidity, different areas have different forest distribution. All kinds of plants grow in the forest.
19. Pond plants include emergent plants, floating plants and submerged plants. There are also many phytoplankton that are invisible to the naked eye. The plants in the farmland are closely related to us. The fundamental difference between agricultural products and crops lies in whether they are sold in the market.
20. Man should not be the master of nature. Every species is a precious wealth of mankind. Many plants are extinct, and many plants are on the verge of extinction, such as Davidia involucrata in China, Liriodendron chinense in China and Metasequoia glyptostroboides in Wuhan.
Six, the animal world
2 1. Various ecological environments provide abundant habitats for the survival of animals. Animals not only live in forests, grasslands and wetlands, but also live in rooms and their surroundings. China is one of the countries with the richest animal diversity.
22. Forests and grasslands are the main habitats of large mammals. The complex plant species in the forest constitute the living environment of various animals, providing them with habitats, foraging and hidden places.
23. Wetlands are important habitats for aquatic animals, especially waterfowl. After the wetland is reduced, many rare and endangered waterfowl will face the danger of extinction.
24. There are great differences between different animals, and there are also differences between individuals of the same species, which make the animal world take on various forms. However, due to the destruction of the ecological environment, many animals are in an endangered state, and human beings must implement sustainable development.
Seven, a member of the biological world-human beings
25. A correct understanding of teenagers' common sense is a new starting point for teenagers' psychology to gradually become healthy and mature. Reproductive phenomenon is a natural and normal phenomenon. Most creatures and life start from a fertilized egg, and human beings are no exception. Women's ovaries produce eggs, and men's testicles produce sperm. The egg is spherical and can't move. The nucleus is in the head, the sperm is tadpole-shaped and can move, and the nucleus is near the center. A fertilized egg is a combination of sperm and egg cells. The process of their combination is called fertilization. Fertilization can be divided into in vitro fertilization (such as frog) and in vivo fertilization (such as human).
26. It takes about 40 weeks (65,438+00 months) for a human embryo to mature in the uterus. The mature fetus gives birth to the mother through the vagina, which is called delivery (voice immunity). Fetus and mother exchange nutrition through placenta and umbilical cord. The best food for babies after birth is breast milk, which is rich in nutrition and antibodies.
27. A person's life is divided into embryo, infancy, adolescence, adulthood and old age, among which infancy and adolescence grow fastest, especially adolescence, which is called the golden age of human growth and is suitable for learning new knowledge and increasing talents. Generally between 10- 18 years old, girls are earlier than boys.
28. In adolescence, the reproductive organs gradually mature, with obvious differences between men and women. Differences in reproductive organs are called primary sexual characteristics, and other differences such as beards are called secondary sexual characteristics.
Eight, a healthy lifestyle
29. Water (60%-70%) is the most important substance that constitutes our body. It, the substance that provides energy for life activities and some important substances all come from food.
30. Water, inorganic salts, sugar, fat, protein and cellulose are the six major nutrients in food. Cellulose is one of the ingredients of human food, also known as dietary fiber. No food in nature can provide all the substances needed by the human body in a balanced way. We should have a balanced diet and keep the diversity of food. The ratio of breakfast, lunch and dinner is 3: 4: 3.
3 1. Smoking is very harmful to health, so teenagers should protect themselves from refusing the first cigarette. The scientific name of the main component of wine is ethanol. It is harmful to human body, and many domestic violence and car accidents are related to it. Teenagers are not fully developed and should not drink alcohol. Drugs are a global public hazard. Drug abuse is self-destructive and harmful to society. Don't try it.
32. Infectious diseases are characterized by infectivity and epidemic. The three basic links are the source of infection, the route of transmission and the susceptible population. Control the epidemic of infectious diseases from all aspects, that is, control the source of infection, cut off the route of transmission and protect susceptible people; The modes of transmission of hepatitis B are: blood, fetus, iatrogenic, sexual contact, close-range life transmission and so on.
33, in the event of an accident, should immediately use the correct method for treatment. The first-aid methods for food and pesticide poisoning are: vomiting, gastric lavage, catharsis and detoxification; When getting an electric shock, cut off the power supply quickly, let the person get an electric shock lie flat, keep warm and give artificial respiration.