--- 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?

A girl calling herself Mary is waiting outside; _____ she come in now?

My book, The House of Hales, is missing. Who ________ have taken it?

----The task is challenging and demanding. Who do you think can make it?---- ___________my partner have a try? I think she is the right person to do it.

—May I do the rest of the work tomorrow?—Yes, of course. You        finish it today.