---Must he remember everything he has learned in the class?---No, he _____.

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

Without gravity, we _____ walk on the ground as freely as we do now. 

—Why don’t you wear your jogging shorts, mum?—Well, my legs are too skinny, if you ______ know. 

The light in his office is out. He_________ left for home.