公共英语考试二级阅读理解模拟题：
　　Because we can feel that things are heavy,we think of weight as being a fixed quality in an object,but it is not really fixed at all.If you could take a one pound packet of butter 4,000miles out from the earth,it would weigh only a quarter of a pound.Why would things weigh only a quarter as much as they do at the surface of the earth if we took them 4 000 miles out into space?The reason is this:All objects have a natural attraction for all other objects;this is called gravitational attraction,but this power of attraction between two objects gets weaker as they get farther apart.When the butter was at the surface of the earth,it was 4 000 miles from the centre(in other words the radius（半径）of the earth is 4 000 miles).When we took the butter 4 000 miles out,it was 8 000 miles from the centre,which is twice the distance.
　　If you double the distance between two objects,their gravitational attraction decreases two times two.If you treble（翻三倍）the distance,it gets nine times weaker(three times three).If you take it four times as far away,it gets sixteen times weaker(four times four)and so on.
　　1、If an object weighed one pound 8 000 miles above the earth,it would weigh on the surface of the earth.
　　A.6 pounds
　　B.4 pounds
　　C.9 pounds
　　D.1/9 pound
　　参考答案：C
　　2、If the distance between two objects is shortened by half,their gravitational attraction will.
　　A.double
　　B.become four times stronger
　　C.be the same
　　D.get four times weaker
　　参考答案：B
　　3、The best title for this passage is.
　　A.The Earth Weight
　　B.Weight in Space
　　C.Changing Weight on the Earth
　　D.Weight on and off the Earth
　　参考答案：D
　　参考解析：本篇短文介绍的是物体在空中和在地球上重量不同的原因，因此恰当的标题应是D.
　　4、We can feel things are heavy because.
　　A.weight is a fixed quality in an object
　　B.they are far away from the centre of the earth
　　C.of the earth's strong attraction for them
　　D.they are not taken away from the surface of the earth
　　参考答案：C
　　参考解析：我们之所以能感觉到重量是因为地球引力的原因，答案为C.
　　参考译文：
　　因为我们可以感觉到东西很重，所以我们认为重量是物体的固定质量，但它根本不是固定的。如果你能从离地球4000英里远的地方拿走一磅的黄油，它只有四分之一磅重。如果我们把它们带到4000英里外的太空，为什么物体的重量只有地球表面重量的四分之一呢？原因在于：所有物体对其他物体都有自然的吸引力，这叫做引力，但是两个物体之间的这种吸引力随着它们距离的拉远而减弱。当黄油在地球表面时，离中心4000英里（换句话说，地球的半径是4000英里）。当我们把黄油取出4000英里时，离中心有8000英里，是距离的两倍。
　　如果你把两个物体之间的距离加倍，它们的引力就会减少两倍。如果你的距离增加了三倍，它就变弱了九倍（三倍三）。如果你把它放在四倍远的地方，它就会弱十六倍（四倍四），等等。