题目内容
My brother has been teaching ________ he was 21 years old.
A.when | B.if | C.for | D.since |
D
试题分析:主句用的是现在完成时态。since,自从……(到现在)现在完成时的标志词。句意:我的弟弟自从21岁就一直在教学。
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题目内容
A.when | B.if | C.for | D.since |