—Why did you leave without a word of warning to John?—But what _____ otherwise? He never listens to me.

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

Susan’s parents have bought a large house with a swimming pool.It      be very expensive.

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

— What are you doing this Saturday?— I’m not sure, but I go to the Rolling Stones concert