--Listen! Tom is singing in the next room.--It _______ be Tom. He has gone to Shanghai.
--- What do you think of pollution of the big factory?--- It’s a serious problem. We should _____ all the people to do something for it.
There is little water in your cup, ________?
--- What are you doing here, Mrs. White?---I'm waiting for my son. He________ back from school.
--- Why are you taking a bag with you?--- I’m going to buy something. The supermarkets don’t _____ free plastic bags to shoppers to protect the environment.
--- Can we find before an earthquake?--- Yes. Some animals will run wildly and some plants will come out in the wrong season.