有道题选项里面有cut down和knock off.答案选的knock off,为什么不可以用cut down

有道题选项里面有cut down和knock off.答案选的knock off,为什么不可以用cut down knock off和knock down的区别 cut down cut off 关于fall down/off 和cut down/off的用法 cut down\cut out\cut off\cut through 的区别? cut off ,cut down的区别 cut off cut down区别 knock it off 和 cut it out 用起来有什么区别啊. cut down,cut down to,cut down on,cut off有什么区别 cut off、cut down、cut away的区别 cut down,cut up,cut off的区别 knock off和knock