When I was walking in the street I saw a plane over my head.A. flies B. flyingC. flew D.

问题补充：

When I was walking in the street, I saw a plane over my head.

A. flies

B. flying

C. flew

D. fly

答案：

A. flies

(答案→)B. flying

C. flew

D. fly

解析：考查感官动词see的用法。see sb. do sth.“看见某人做了某事”；see sb. doing sth.“看见某人正在做某事”；句意“当我在街上走时，我看见一架飞机在上空飞行。”故选B。