--- How old are you, madam?--- If you _______ know, I’m twice my son’s age.
--- Do you doubt ____ he’ll be fired by the school? --- No, not a bit. But I doubt ____ he will bury himself into study.
His brother met him at the Great Theatre yesterday afternoon, so he ____ have attended your lecture.
--- Would you help sweep the floor? --- _____ . I’d rather water the flowers.
The police________ him to see if he had a gun.
I hope, first of all, that we shall never lose _____ heart in face of _____ failure.