the floor I found his pen lying on the ground. A. While sweepingB. While sweptC. If swee

问题补充：

the floor, I found his pen lying on the ground.

A. While sweeping

B. While swept

C. If sweeping

D. If swept

答案：

(答案→)A. While sweeping

B. While swept

C. If sweeping

D. If swept

解析：

此题考查while引导的短语作时间状语。现在分词短语表示动作正在进行。