—If there are ________ people driving, there will be ________ air pollution.—Yes, and the air will be fresher.
A. less; less
B. less; fewer
C. fewer; fewer
D. fewer; less
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Of all the students he is more clever. 横线上的词正确吗？
A. 对
B. 错
She is more prettythan her sister.横线上的形容词使用正确吗？
A. 对
B. 错
物质的粒子跃迁分辐射跃迁和非辐射跃迁，简述这两种跃迁的区别。
一般化学反应的活化能约为KJ/mol。
A. 20-40
B. 40-60
C. 40-400
D. 60-80
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