Mr. Zhao has taught in our school _____ 3 years ago. A. since B. for C. /
---Could we buy a piano, Jack?---I’m afraid there ______ enough room for one in the house.
--Could you please _____ in the room?--Oh, I’m sorry.
_____ have you been swimming? For five years.
It’s really cold today, ______ ?
---He’s never been to an aquarium.---_______.