Tom, you ____ leave all your clothes on the floor like this.

—Would you like _______ or shall we go by bus?— I prefer _______,but we have to take a taxi, for time is short.

I ________worry about my weekend—I always have my plans ready before it comes.

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

I ______ tell you with certainty that he won’t be able to finish it before the deadline.