一、表达意思不同
1、turn off:关掉,关闭;拐弯,使转变方向;使失去兴趣。
2、turn down:减小,关小,调低;拒绝。
二、固定搭配不同
1、turn off:Turn off the engine 关闭引擎 ; 封闭引擎 ; 熄掉汽车 ; 熄掉。
2、turn down:turndown ratio 调节比;极限负荷比。
例句:
1、Don't turn off the computer before closing all programs or you could have problems.
在关闭所有程序之前不要关掉电脑,否则可能会出现问题。
2、The jet began to turn off the main runway.
那架喷气式飞机开始拐出主跑道。
3、Tom had to turn down the invitation to the party last weekend because he was too busy.
汤姆太忙了,不得不拒绝上周末的聚会邀请。