用am, is 或are 填空。
(1)These postcards ______ great. This _____ the Great Wall
(2)_____ you a driver?   Yes, I _____.
(3)He ____ going to visit his grandpa.
(4)Mexico ______ in the west.
(5)Look, they _____ dancing.
(6)Sam _____from England.
(7)There _______ lots of tall buildings in our city.
(8)There________ a bird in the tree.
(9)There _______ some milk in the bottle.
(10)There _______ a blackboard and four computers in the classroom.
(11)There _______ two teachers and a student in the office.
(12)There _______ a Chinatown in New York.