We used to see each other _____, but haven’t heard from him since last year.
----- Where did you ______ our chemistry teacher?----- It was in the supermarket ______ I saw him.
Yuan Longping makes ____ possible to produce more crops in the same fields with this special strain of rice
Please ______ the traffic regulations.
Only then ______ how much damage had been caused.
Before he came , I’d finished _______ the whole book.