The earth is not the only body that travels around the sun. With it are eight other planets, fellow members of the sun’s family.
Two of them, Mercury (水星) and Venus, are nearer while the other six, namely Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, also in their given order from the sun, are farther from the sun than the earth is. The farther they are, the longer trips they make around the sun. People noticed long ago that these traveling bodies moved around in the sky in definite paths. It is a force called gravity that holds them in their paths.
We know that every little bit of matter in the universe pulls upon every other bit of matter. The pull between two bodies is proportional (成比例的) to the product of their masses. Because the sun is so large the pull between the sun and the planets are thus great. If it were not for this pull, the planets would fly off into space. In the same way there exists a pull between the earth and the moon, which keeps the moon traveling in its orbit around our planet, the earth. Gravity holds you to its surface, and pulls back to it the ball which you throw into the air. Of course the ball also pulls on the larger earth but the earth is so much larger that the pull is not noticed.
Now remember that large bodies exert a greater pull than smaller ones which contain less material. But each object in the universe, no matter how small, pulls on all other objects to some degree.
小题1:There are ________ that travel around the sun in the sun’s family.
A．nine planets
B．eight planets
C．one star and ten planets
D．the earth and the sun小题2:Which two planets make the longest trips around the sun among all the planets in the solar system?
A．Mercury and Venus.
B．Neptune and Pluto.
C．Saturn and Uranus.
D．Mars and Jupiter.小题3:From the passage we can see__________
A．all the objects, big or small, must exert the same pull on one another
B．large objects exert the same pull on anybody as small objects
C．small objects exert the same on large ones
D．each object in the universe exerts a pull on all other objects小题4:From the sentence “The pull between two bodies is proportional to the product of their masses.” We can infer that the pull between__________
A．the sun and the moon is greater than between the sun and the earth
B．the earth and the moon is greater than that between the sun and the earth
C．the sun and the earth is greater than that between the earth and the moon
D．the sun and the earth is the same as that between the earth and the moon
小题1:A
小题2:B
小题3:D
小题4:C
题目分析：文章介绍了太阳系围绕太阳转的星球相互的关系，引力的大小并且解释了这种现象的原因。
小题1:细节题：从第一段的句子：The earth is not the only body that travels around the sun. With it are eight other planets, fellow members of the sun’s family.可知共有9个星球围绕着太阳转。选A。
小题2:细节题：从第二段的句子：Neptune and Pluto, also in their given order from the sun, are farther from the sun than the earth is. The farther they are, the longer trips they make around the sun. 可知Neptune and Pluto.是绕太阳的路程最远。选B
小题3:细节题：从最后一段的句子：But each object in the universe, no matter how small, pulls on all other objects to some degree.可知答案是D
小题4:句意理解题：从后面的句子：Because the sun is so large the pull between the sun and the planets are thus great.可知体积越大，天体的引力就越大。选C
点评：本文属于科普文章，细节题居多，答题时在文章找到对应的地方，用笔进行标记，这有利于后期有时间检查时可以立刻找到答案的位置。仔细理解作者所讲的意思，再结合选项，通过排除法和自己对全文的把握，选出正确答案。