While the book on the top shelf , you need to be very careful .A. to reachB. reachingC. re

发布时间：2020-08-17 00:13:07

While      the book on the top shelf , you need to be very careful .
A. to reach
B. reaching
C. reach
D. are reaching

网友回答

A. to reach
(答案→)B. reaching
C. reach
D. are reaching
解析：考查省略式，因为英语中如果主从句的主语一致的话，可以省略从句的主语和be动词，while reaching=when (you are) reaching ,句意是：当你够架子上的书时，你需要小心。选B。
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