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.
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.