I haven't seen you before.这里before就应该用现在完成时.
I did the homework the day before yesterday.这里根据the day before yesterday就是用过去时.
请根据不同的语境来判断.
I haven't seen you before.这里before就应该用现在完成时.
I did the homework the day before yesterday.这里根据the day before yesterday就是用过去时.
请根据不同的语境来判断.