Mary heard somebody call her,so she turned ( ) to see who it was.

turn around 是转身的意思,turn out有两个常用的意思：（1）“结果是,结局是”,后面常接to be 或者that 语句.
It turned out that he was lying.结果是他在说谎.
(2)出现,出场
比如：A vast crowd turned out to watch the match.大群的观众到场观看比赛