I borrowed the book three weeks ago.同义句转换 I _ _ the book since three weeks ago.I borrowed the book three weeks ago.同义句转换 I _ _ the book since three weeks ago.现在完成时since和for什么的弄不懂 have+v(pp) have什么时候用had
问题描述：
I borrowed the book three weeks ago.同义句转换 I _ _ the book since three weeks ago.
I borrowed the book three weeks ago.
同义句转换 I _ _ the book since three weeks ago.
现在完成时since和for什么的弄不懂 have+v(pp) have什么时候用had
答
I _has _borrowed_ the book since three weeks ago.
现在完成时，since。。。。表示自。。。时候开始
for。。。表示行为持续了多长时间。
过去完成时用had
答
have kept现在完成时的since 后加 点时间for 加 段时间比如：I haven't seen you since we graduated.I haven't seen you for 5 years.有一个过去时间,在描述在这个时间点之前发生的动作,用had doneI had done my wo...