John waited at the bus-stop for nearly half an hour the bus finally arrived .A. whenB. as

发布时间：2020-08-17 14:33:05

 John waited at the bus-stop for nearly half an hour      the bus finally arrived .
A. when
B. as
C. before
D. while

网友回答

A. when
B. as
(答案→)C. before
D. while
解析：before引导时间状语从句，公共汽车来之前，我已等了将近半个小时了。故选C。
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