Will you think that boiling eggs is particularly simple? Water + eggs cook a while on OK. really is this so? In fact, there are some tips for boiling eggs.　　1, soak the water before cooking eggs, it is best to put the eggs into cold water for a while, and then into the cold water pot to boil, so that the eggshell is not easy to crack. Of course, this is only one of the ways to keep the shape of the egg intact.　　2, fire Boiled eggs if the fire, easy to cause rapid expansion of the air inside the shell and lead to shell cracking; if you use a small fire, and prolonged the time to cook eggs, and not easy to grasp the degree of good eggs old and tender. Practice has proved that boiled eggs to medium fire is most appropriate.　　3, time After determining the size of the fire, as long as accurately grasp the time to cook eggs, you can control the degree of tenderness of the eggs at will. For example, soft boiled eggs, boil water for 3 minutes. At this time, the egg white solidified, the yolk is still fluid; cook loose eggs, boil the water and cook for 5 minutes. At this time the egg white solidified, the yolk was thick liquid, soft and smooth; hard-boiled eggs, boil the water and cook for 7 minutes. At this time, the egg white solidified, the yolk is dry. It should be noted that hard-boiled eggs do not extend the time at will. Because the eggs in the boiling water cooking time is too long, more than 10 minutes, the eggs will occur within a series of chemical changes, thereby reducing the nutritional value of eggs.　　4, stirring In order to make the egg yolk solidified in the middle of the egg white, should be in the egg in the pot with a hand spoon constantly stirring in one direction, so that the water in the pot was swirling, until cooked. As for what principle this is, it must be related to the centrifugal force and centripetal force in physics.