Listen! Is Mary singing in the next room?—No. It _______ be Mary．She has gone to Shanghai for an important meeting.

Jet Li to Guangzhou for charity . He’ll come back in two days.

Did you watch the basketball match last night? —Yes. Jeremy Lin didn’t play ______ he did last week.

Having been in hospital for two months, _______he was going to catch up with his classmates.

Some people waste too much water. They don’t believe that it can__________some day.