You may not go out until your work is done.这句话若要改成before连接句子怎么改?You may not go out___your work is done.A.before B.until C.where D.as请问下面的Before your work is done,you may not (can not)go out.这里的before从句必须放前面吗？如果可以放后面,那这道题的答案不就是A,B了？有没权威点的语法解释啊。找到一个比较权威的语法解释:希望对以后有同样问题的人有用:不少的语法书上说，before引导的从句习惯上不与否定的主句连用，要用until。实际上二者都可以，有时在意义上有些区别。试比较：He didn't arrive until I returned.直到我回来时他才到达。He did not arrive before I returned.在我回来之前他尚未到达。I didn't manage to do it

You may not go out until your work is done.
这句话若要改成before连接句子怎么改?
You may not go out___your work is done.
A.before B.until C.where D.as
请问下面的
Before your work is done,you may not (can not)go out.这里的before从句必须放前面吗？
如果可以放后面,那这道题的答案不就是A,B了？有没权威点的语法解释啊。
找到一个比较权威的语法解释:
希望对以后有同样问题的人有用:
不少的语法书上说，before引导的从句习惯上不与否定的主句连用，要用until。实际上二者都可以，有时在意义上有些区别。试比较：
He didn't arrive until I returned.直到我回来时他才到达。
He did not arrive before I returned.在我回来之前他尚未到达。
I didn't manage to do it until you had explained how.直到你解释了如何干，我才设法完成了那项工作。
I didn't manage to do it before you had explained how.你解释了如何干之后，我才设法完成了那件工作。