"something that dampens one's spirits" recorded by 1971 (said to have been in use since 1968), from verbal phrase turn off "stop the flow of" (1850), from turn (v.) + off (adv.). Turn-off (n.) as "place where one road diverges from another" is from 1881.
权威例句
1. For what do we live, but to make sport for our neighbours, and laugh at them in our turn?
我们活着是为了什么?不就是给邻居当笑柄,再反过来笑他们。
2. He said they should turn their fire on the Conservative Party instead.
他说他们应该掉转枪口,向保守党开火。
3. Today I might hesitate to turn in a burglar.
现在让我把入室窃贼送交警方,我可能会有所顾虑。
4. Sometimes things don't turn out the way we think they're going to.
有时事情并不像我们认为的那样发展。
5. The river widens considerably as it begins to turn east.