---Who can it be that hasn’t handed in his composition?
---It ______ be Robinson. He ______ it in yesterday.

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

Car lovers often organize field sports in our country. It is an activity that they ______ without the benefits of a car.

—You didn’t go to Europe, why?
—I _____ this morning, but I _____ to Shanghai because of an emergency .

There is only one who is capable of setting limits to your growth, and it _____ well be you.

We used to work in the same office and we _________ have coffee together.?

The boss has given everyone a special holiday, so we _____ go to work tomorrow.

Walking in space _________sound easy, yet great care and skills are required.

What would have happened ________, as far as the cliff?

My pain _______ apparent the moment I walked into the room, for the first man I met asked sympathetically， “Are you feeling all right?”