Question

Every object has weight. But the center of its weight is not always in the middle of the object. If the top of an object is heavier than its bottom, it will fall over easily. We say that its center of gravity(重力) is high. But if the bottom is heavier, it won’t fall easily. Then we say that its center of gravity is low.

Look at the first picture. This empty box must fall over, because its center of gravity (C) is not above the line of its bottom (AB).

Now look at the second picture. There are some heavy things in the bottom of this box. It will not fall, because its center of gravity is above its bottom.

1. Box _____________will not fall.

A.      B.     C.    D.

2.The main idea of the passage is _________.

A.that everything has weight

B. a low center of gravity

C. a high center of gravity

D. why things fall over

Answer

1.A

2.D

【解析】

试题分析：这篇短文主要讲述了由于物体重心的位置不同，会导致物体是否会倾倒，并以两个物体为例子进行了说明。

1.A判断推理题。根据文中it will not fall, beause its center of gravity is above its bottom.判断得知，如果物体的重心在它底线之上就不会倒，故选A。

2.D主旨大意题。这篇文章主要讲述了物体在什么情况下会倾倒，什么情况下不会，故选D，为什么物体会倾倒。

考点：科普类短文阅读。