He had to before they finished the course because they were not well disciplined.A. drop i

发布时间：2020-08-17 14:07:19

He had to     before they finished the course because they were not well disciplined.
A. drop in
B. drop out
C. drop off
D. drop by

网友回答

A. drop in
(答案→)B. drop out
C. drop off
D. drop by
解析：这里的短语意思各不相同，drop out 退学,drop in /drop by　顺便拜访，drop off 下降，减少。
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