he's been singing for five years（改为同义句）
问题描述：
he's been singing for five years（改为同义句）
答
It's 5 years since he sang
答
He's been singing for five years.
= He has been singing as long as five years.
= He has been singing since five years ago.
一楼答案如果把sang改成began/started to sing或began/started singing,则才是正确的.