he has been a soldier for three years.改为同义句:It is three years --------- ---------- ---------

问题描述:

he has been a soldier for three years.改为同义句:It is three years --------- ---------- ---------
the army.

It is /has been three years since he became a soldier.
固定句型:It is /has been +一段时间+since.不管是用is还是has been ,since从句都用过去时