题目内容
9．
Every object has weight．But the center of its weight is not always in the middle of the object．If the top of all object is heavier than its bottom （底部），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 is some heavy iron （铁） in the bottom of this box．It will not fall，because its center of gravity is above its bottom．
54．If the bottom of an object isAits top，it will fall over easily．
A．1ighter than
B．heavier than
C．no heavier than
D．as heavy as
55．Please point out which box will not fall．C
56．The reason why the Leaning Tower of Pisa does not fall is thatC．
A．the top of the tower is heavier than its bottom
B．the bottom of the tower is not heavier than its top
C．its center of gravity is still above the line of its bottom
D．its center of gravity is not above the line of its bottom．
分析 文章大意：每个物体都有重量．但其重心并不是总是在物体的中间．如果上面所有的对象比其底部较重，它会轻易摔倒．我们说，它的重心高．但如果底部较重，它不会很容易摔倒，我们说它的重心低．
解答 54-56：ACC
54题答案：A 细节题．根据第一段If the top of all object is heavier than its bottom （底部），it will fall over easily，可知如果上面所有对象比其底部较轻，它会轻易摔倒，故答案是A．
55答案：C 细节题．根据第三段Now look at the second picture．There is some heavy iron （铁） in the bottom of this box．It will not fall，because its center of gravity is above its bottom．，可知选C，因这它的重心在底部，故答案是C．
56题答案：C 细节题．根据第一段But if the bottom is heavier，it won't fall easily，Then we say that its center of gravity is low，可知比萨塔不会倒是因为它的重心没有高过底部，故答案是C．
点评 本文是一篇日常生活类阅读，题目涉及多道细节理解题，做题时结合原文和题目有针对 性找出相关语句进行仔细分析，结合选项选出正确答案．推理判断也是要在抓住关键句子的基础上合理的分析才能得出正确的答案．
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