As it turned out to be the most important meeting in the year, you ____ so casually. 

—Look at the sign! —Oh, I see.We _______ waste water.

All of us must do_______ to help protect the environment，or we will have more hazy weather雾霾天气.                                    

 ---The book _____ be Tom’s.---No, it _____ be his. There’s a name on the book. It’s Jim’s.

—What do you need to say?—No person         smoke or carry a lighted cigarette in this special room.