问题补充:
My brother has been teaching he was 21 years old.
A. when
B. if
C. for
D. since
答案:
A. when
B. if
C. for
(答案→)D. since
解析: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。
时间:2019-07-18 04:53:13
My brother has been teaching he was 21 years old.
A. when
B. if
C. for
D. since
A. when
B. if
C. for
(答案→)D. since
解析: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。