To our surprise the stranger to be an old friend of my mother’s.A. turned outB. turned u

问题补充：

To our surprise the stranger to be an old friend of my mother’s.

A. turned out

B. turned up

C. set out

D. set up

答案：

(答案→)A. turned out

B. turned up

C. set out

D. set up

解析：turn out 意为“结果是，原来是”等；turn up 意为“找到，发现，出现，开大音量”等；set out 意为“开始，出发，陈述”等；set up 意为“设立，竖立，架起，升起，创(纪录)，提出”等。