9. In the first sentence of the second paragraph of the article, it is pointed out that asteroids are celestial bodies larger than meteors that cross the night sky. It can be seen that they are celestial bodies with the same nature, but different sizes.

10.？ The last two sentences of the second paragraph of the article point out that most asteroids orbit the sun. Being far away from the earth will not threaten us. But there are still thousands of asteroids that may hit the earth. It can be seen that the possibility of an asteroid hitting the earth is very small, but the danger does exist. Item b is a conceptual error. The third paragraph of the article points out that it takes 25 years to determine the position of most asteroids. In the fifth paragraph of the article, it is also mentioned that an asteroid with great destructive power may collide with the earth once every 500,000 years, indicating that item B is wrong. Item C is not mentioned in the article, and item D is inconsistent with the content of the article.

1 1.？ Note that in the first sentence of the last paragraph, "cure" refers to the solution, that is, using nuclear weapons to change the orbit of asteroids, while "disease" refers to the possibility that asteroids may collide with the earth. It can be understood from this sentence that nuclear weapons will bring worse consequences than asteroids and bring more panic to people. So choose item B.

12.？ The selection should be based on the full text. The full text repeatedly emphasizes the danger of asteroids hitting the earth, but does not mention that it will happen in the near future, so item B is excluded. Finally, the article points out that nuclear weapons against asteroids will destroy the earth while changing the orbit of asteroids, so it can be concluded that the feasible scheme of asteroid hitting the earth needs further exploration. Item A is a fact, not a conclusion.