I didn't know he came back___I met him in the street.A.sinceB.when C.until D.after正确答案是：

I didn't know he came back___I met him in the street.
A.sinceB.when C.until D.after
正确答案是：

C not ...until 直到...才...
我直到在街上遇到他才知道他回来了.