He is a very careful man, but he ________ make mistakes which seem ridiculous

He suggested the person referred ________ put into prison.

 “Mike is often absent from class.” “Tell him he _________ answer for it if he goes on behaving like that.”

It's high time that you ________ even harder at your lessons as the exam is around the corner.

--I can’t understand why our boss is late. --He _____the early bus.