1 . I have often thought it would be a blessing if each human being ______ (strike) blind and deaf for a few days at some time during his early adult life. (所给词的适当形式填空)

2 . We are still at the airport．If it weren’t for the delayed flight, we _______ the concert right now．

A．can be enjoying	B．must have enjoyed
C．would be enjoying	D．should have enjoyed

3 . --Would you mind if I _____ here?
--__________. Go ahead, please.

A．smoking; Yes, I do	B．smoking; Of course
C．smoked; No, not at all	D．smoke; No

4 . Don’t you think the world would be an easier place to live in, if we all ________ the same language?

A．speak	B．had spoken
C．spoke	D．would speak