—It ___________ be Tom. He has gone to his hometown to visit his grandparents.
A:can
B:can't
C:must
D:mustn't
(____)A. There is a school in my village.
(____)B. There is a river on the mountain.
(____)C. There're many animals in the forest.
(____)D. There is a tree behind the building.
(____)E. There is a lake near the house.
①控制污染物的排放 ②植树造林 ③化工厂停止排放污水 ④禁止焚烧秸秆.