It's very difficult to learn English well, but you can't _____.
A couple of years ________ since the earthquake took place in Wenchuan.
—My father’s just come back from work, __________?— __________. He is having a rest in the room.
— I don’t like my life in this school. I sometimes feel so_____ and helpless.— I don’t think so. You are never____ because all your classmates are ready to help you.
— When did your parents __________?— They ___________ for 20 years.
Is _______ air pollution ________ serious problem now?