Question

【題目】 Every object has weight．But the center of its weight is not always in the middle of the object．If the top of ail 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 (鐵) in the bottom of this box．It will not fall，because its center of gravity is above its bottom．

【1】If the bottom of an object is its top，it will fall over easily．

A．1ighter than B．heavier than

C．no heavier than D．a(chǎn)s heavy as

【2】Please point out which box will not fall．

【3】The reason why the Leaning Tower of Pisa does not fall is that ．

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

Answer 1

【答案】

【1】A

【2】C

【3】C

【解析】

試題分析：短文大意：每個物體都有重量。但其重心并不總是在物體的中間。如果上面所有對象比其底部較重，它會輕易摔倒。我們說，它的重心高。但如果底部較重，它不會很容易摔倒，我們就說它的重心很低。

【1】A細節(jié)理解題。根據(jù)第一段中If the top of ail object is heavier than its bottom (底部)，it will fall over easily．可知如果上面所有對象比其底部較重，它會輕易摔倒。所以該選A。

【2】C細節(jié)理解題。根據(jù)第三段Now look at the second picture．There is some heavy iron (鐵) in the bottom of this box．It will not fall，because its center of gravity is above its bottom．的描述可知該選C，因為它的重心在底部。

【3】C細節(jié)理解題。根據(jù)第一段末But if the bottom is heavier, it won’t fall easily, Then we say that its center of gravity is low．可知比薩斜塔不會倒是因為它的重心沒有高過底部，所以該選C。