---- May I smoke here?--- If you      , choose a seat in the smoking section.

—Dad，can I go to the movies tonight?--Sure，but you__come back home before 9 o’clock.

-----        you swim?   ----- Yes,I can.

--The research on the new bird flu virus vaccine is challenging and demanding. Who do you think can do the job?--________ my students have a try?

—Must I finish my homework now?—No, you _______.