– Why did they help Mrs Brown with her work?
– Because she was .
A. an old friend of them
B. the friend of them
C. on the their friend
D. a good friend of theirs
网友回答
A. an old friend of them
B. the friend of them
C. on the their friend
(答案→)D. a good friend of theirs
解析：句意：他为什么帮助布朗夫人做她的工作？——因为她是他们的一个好朋友。Of在表示所有关系时，后面接名词，them是人称代词。选项ABC结构有误，故选D，名词性物主代词做介词宾语。