—We want someone to design the new art museum for us?—          the young fellow have a try?

 Sir, you _______ be sitting in this sitting room. It is for women and children only.

We ________the difficulty together, but why didn’t you tell me?

--Jack, is this your jacket?--No, it _______ be my jacket. My jacket is black but this one is blue.

The doctors are doing all that they _____, but the old man is still not breathing properly.