— My sons are not a little restless.— Oh? Boys _______ be boys．

—Whose volleyball is it? —It ________ Carla’s. She doesn’t like volleyball at all.

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

—Is Jack on duty today? —It ______ be him. It is his turn tomorrow.

 You ______ to the meeting this afternoon if you have something important to do.