问题补充:
The poor old man with his two daughters in the street.
A. was seen to beg
B. were seen to beg
C. was seen begged
D. were seen begging
答案:
(答案→)A. was seen to beg
B. were seen to beg
C. was seen begged
D. were seen begging
解析:句子主语是poor old man,所以谓语动词用单数,see动词用于被动语态中,宾补的不定式要还原to出来。