turn作为动词和名词构成众多的短语，今天挑一部分最常考最重要的进行讲解。
turn用作动词时：
1.turn down
①调低（音量等），调小（反义词turn up）
I wonder if you could turn down your radio a bit. 不知你能否把收音机的声音调小一点。
②拒绝（同义词refuse）
When I applied to join the expedition, Shackleton turned me down because he thought I was too young and wasn’t qualified. 当我申请加入探险队时，沙克尔顿拒绝了我，因为他认为我太年轻，不够格。（新人教版选择性必修3）
2.turn up
①调大（音量），开大（反义词turn down）
Would you please turn up the TV? 请你把电视声音开大一点好吗?
②出现，露面
He promised that he would come, but he hasn’t turned up yet. 他答应要来的，但到现在还没有出现。（2012陕西卷）
3.turn in上交（同义词hand in）
Turn in/Hand in all your homework when you return from vacation. 你假期回来后把所有的家庭作业都交上来。
4.turn on打开（煤气，水，电灯，电脑等）（反义词turn off）
Please help me turn on the light. 请帮我打开灯。
5.turn off关闭（煤气，水，电灯，电脑等）（反义词turn on）
Turn off the computer when you leave. 离开的时候把电脑关掉。
6.turn out
①证明是，结果是，原来是
It turned out that his brother died of a heart attack. 原来他哥哥死于心脏病发作。
The weather turned out to be pretty nice. 结果天气很好。
②参加，出席
He also saw hundreds of delighted students who had turned out to welcome him. 他还看到数百名学生高兴地来欢迎他。（新外研版必修3）
③关掉，熄灭
Night came as if a lamp was being turned out. 夜幕降临了，仿佛一盏灯在被熄灭了。
7.turn over
①翻身，翻转
He always turned over in bed and was difficult to get to sleep. 他总是在床上翻来覆去，很难入睡。
②反复考虑
He turned over the math problem in his mind, so he didn’t hear his mother call him. 他在脑子里反复琢磨着这道数学题，所以没有听到妈妈叫他。
③移交
He turned over the business to his son. 他把生意移交给了儿子。
8.turn to
①转向
Interestingly, audiences have in recent years turned to television series. 有趣的是，近年来观众转向了电视剧。（新外研版必修2）
②求助于
He always turns to the police for help when he is in trouble. 他遇到麻烦时总是向警察求助。
turn用作名词时：
1.It’s one’s turn to do sth轮到某人做某事
It’s your turn to clean the floor. 轮到你打扫地板了。
2.in turn依次，反过来
The customer praised the manager, who, in turn, praised his staff. 顾客表扬了经理，经理反过来也表扬了他的员工。（北师大版第三册）
They shook hands with the hero in turn. 他们依次与英雄握手。
3.take turns轮流，依次
We took turns helping him with his lessons.我们轮流帮助他补习功课。
