This street is very crowded at this time of day.You have to be very cautious while .A. to

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A. to drive
B. being driven
(答案→)C. driving
D. having driven
解析：句意：街上这个时候很拥挤，开车的时候，你要小心。这里使用了时间状语从句的省略，完整的是：You have to be very cautious while you are driving.当主从句的主语一致的时候，可以省略从句的主语和be动词，所以选C。