He insisted the person referred ______ put into prison at once.

It ____ be our headmaster. He has gone to Beijing.

—Who did it?—      .you ask?It was Joe,of course.

--- I’ll tell Mary about our changes tomorrow. --- What? You ______ her yesterday. 

— Do you know where David is ? I couldn’t find him anywhere. — Well. He ______ have gone far –his coat’s still here.