——Coach,can I continue with the training?——Sorry,you can't ______ you haven't recovere——Coach,can I continue with the training?——Sorry,you can't ______ you haven't recovered from the knee injury.先看这两个选项A:as B :before 答案是as.为什么before不行?就是在你没有恢复之前你不能训练.退一步说,如果表达你没有恢复之前你不能训练,怎么改造这个句子?

-----Coach,can I continue with the training?
-------Sorry,you can't (before) you recovered from the knee injury.

as是表示原因的，你不能继续训练，因为你的膝盖还没有康复。
如果用before的话应这么说：you can't before you have recovered from the knee injury.
意思是：在你康复之前，你还不能继续训练。言外之意就是你康复之后才能继续训练

A.How's that B.What is it C.Why don't you D.What do you think 答案究竟是什么？ B C？ A 怎么了？

as在这里翻译成因为，as引导原因状语从句。
改句：You can't continue the train until you recover from the knee injury.用 not ...until...引导条件状语从句

楼主啊
如果你用before
应该是
Sorry,you can't before you have recovered./ Sorry,you can't before your recovery.
你双重否定不就表肯定了吗OTL...
如果你要改造
可以写成
You aren't supposed to unless you have recovered,I'm afraid.