There is a bird in the sky.A. flyBflyingC. fliesD. to fly

问题补充：

There is a bird in the sky.

A. fly

Bflying

C. flies

D. to fly

答案：

A. fly

(答案→)B. flying

C. flies

D. to fly

解析：本题为固定搭配，there be sb/sth doing sth，故选B