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问题 填空题

由于土壤导热率（）空气的导热率，地温的变化比气温的变化要慢得多。

答案

参考答案：小于

选择题

太阳活动所产生的带电粒子流到达地球后，可能造成的影响有

①地球各地出现极光现象              ②磁针不能正确指示方向 

③GPS定位系统将受到干扰             ④我国北方出现极昼现象

A．①②

B．②③

C．①③

D．③④
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选择题
Mark was a student at this university from 1999 to 2003, _____ he studied very hard and was made
chairman of the Students' Union.

A. during which time
B. for which time
C. during whose time
D. by that time
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