1 . The polluted air in the city has been badly ________ (endanger) the health of the residents.   (所给词的适当形式填空)

2 . The polluted air in the city has been badly e__________ (危害) the health of the residents. （根据中英文提示填空）

3 . Many ______animals, such as the Malayan sun bear remain in danger of dying out.

A．endanger

B．endangered

C．dangerous

D．danger