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问题 不定项选择

不同原子核的比结合能是不同的，由比结合能曲线可以看出，中等质量原子核的比结合能最大，轻核和重核的比结合能都比中等质量的原子核要小。由此可以确定，下列哪些核反应能释放大量核能[ ]

A．中等质量的原子核结合成质量较大的重核

B．质量较大的重核分裂成中等质量的原子核

C．中等质量的原子核分裂成质量较小的轻核

D．质量较小的轻核结合成中等质量的原子核

答案

BD

单项选择题

Not everyone in the world requires the same amount of living space. The amount of space a person needs around him is a cultural difference, not an economic one. Knowing your own psychological space needs is important because they ply affect your choices, including, for example, the number of bedrooms in the home. If you were brought up in a two child family and both you and your sister or brother had your own bedrooms, the chances are if you have two children or more, that you also will offer separate bedrooms for them. In America, for example, they train people to want to have their own rooms by giving them their own rooms when they are babies. This is very unusual in the world. In many other countries, the baby sleeps in the same bed with his parents or in bed near them.
The space in the home also shows a lot about psychological space needs. Some families gather closer to each other and the size of their house has nothing to do with it. Others have separate little corners where family members go to be alone.
Although it is true that psychological space needs are not decided by economic reasons, they sometimes have to be changed a little because of economic pressure. It is almost impossible, however, to completely change your psychological space needs.

The first sentence in Paragraph 1 "Not everyone in the world requires the same amount of living space" means ______.

A．Not two people need exactly the same amount of living space
B．Living space requirements are not always the same
C．The world requires the same amount of living space
D．Nobody needs a required amount of living space
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单项选择题

吊车、升降机等昼间施工噪声限值等效声级为（）Leq[db（A）]。

A、55

B、65

C、80
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