It was the President himself______ opened the door．

Look! It must be Jack on the playground.—It _____ be him. Because I saw him enter the school library just now.

I am really surprised that a policeman in his car __________ have hit several common pedestrians, killing one and injuring three.—-Yes, If one __________ ask for trouble, what can we say?

______, a man who expresses himself effectively is sure to succeed more rapidly than a man whose command of English is poor.

My son is learning English. What dictionary shall I buy for him? — What about this one? It is ____for beginners. [ ]