The old man was taking a walk by his grandson. A. supportingB. supported C. being suppor

问题补充：

The old man was taking a walk, by his grandson.

A. supporting

B. supported

C. being supported

D. having supported

答案：

A. supporting

B. supported

C. being supported

D. having supported

解析：句意为“这位老人在他孙子的搀扶下散步。”