This blue car ____________ be Bob’s bcause his car is black.

We ________ like to thank the honest boy.

—Listen！Helen is singing in the next room.—It _____be Helen .She has gone to Beijing.

--- 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?

Students ___________ remain in their seats until all the papers have been collected.