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问题 选择题

如图所示的电路，电源电压不变，闭合开关S后，电灯L1、L2都发光，一段时间后，其中一盏电灯突然熄灭，电压表V1的示数变大，电压表V2的示数变小，则产生这一现象的原因是

[ ]

A.灯L1灯丝烧断了

B.灯L2灯丝烧断了

C. 灯L1短路

D.灯L2短路

答案

答案：D

改错题
短文改错。
      此题要求改正所给短文中的错误。对标有题号的每一行作出判断：
     如有错误（每行只有一个错误），则按下列情况改正。
     此行多一个词：把多余的词用斜线（\）划掉，在该行右边横线上写出该词，并也用斜线划掉。
     此行缺一个词：在缺词处加一个漏字符号（∧），在该行右边横线上写出该加的词。
     此行错一个词： 在错的词下划一横线，在该行右边横线上写出改正后的词。
     注意：原行没有错的不要改。
An American and a Frenchman decided to cross the sea
between France and England in the balloon in 1784. High
over the water, they discover a hole in the balloon. The
hole became bigger and bigger. The air keeps the
balloon up was escaping quickly and the balloon is
coming up. The two men threw all their equipment into 
the water to make the balloon light. It started to rise
higher again. So it was still too close to the water.
Finally, the men threw away most of his clothes to
save themselves. The crowd waiting for to greet them in
England was very surprised see this when the balloon 
landed in front of them. 		1. _____
2. _____
3. _____
4. _____
5. _____                     
6. _____
7. _____
8. _____
9. _____
10. _____
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单项选择题

下列关于DNA分子和染色体数目的叙述，正确的是（）

A.有丝分裂间期细胞中染色体数目因DNA复制而加倍

B.有丝分裂后期细胞中DNA分子数目因染色体着丝点分裂而加倍

C.减数第一次分裂后细胞中染色体数目因同源染色体分离而减半

D.减数第二次分裂过程中细胞中染色体与DNA分子数目始终不变
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