_______by his granddaughter,thr old man walked very slowly.

题目

_______by his granddaughter,thr old man walked very slowly.
单选：A.Being supparted 老师说这是 正在被搀扶?
B.Supparted 被搀扶?
C.To suppart 要加宾?
D.Be suppsrted 被动式不是be done 干嘛不选D?
为什么选B,我要各个选项的详细解释,
我认为A D都比B有理由,C要加宾是为什么?

答案