如no, not, never, seldom, little, hardly, scarcely, at no time决不, by no means, on no account, in no case, many a time, under no circumstances, in no way, many a time, not until… 等。例如：
Never have I seen such a performance. 从未见过如此糟糕的表演。
Nowhere will you find the answer to this question. 无论如何你不会找到这个问题的答案的。
Not until the child fell asleep did the mother leave the room. 母亲一直到孩子入睡后离开房间。
当Not until引出主从复合句，主句倒装，从句不倒装。即：后倒前不倒。注意： 如否定词不在句首不倒装。例如：
I have never seen such a performance.
—never have I seen such a performance.
The mother didn’t leave the room until the child fell asleep.
—not until the child fell asleep the mother did leave the room.
1） Why can’t I smoke here?
At no time___ in the meeting-room
A. is smoking permitted B. smoking is permitted
C. smoking is it permitted D. does smoking permit
2） Not until the early years of the 19th century ___ what heat is.
A. man did know B. man know C. didn’t man know D. did man know
答案D. 看到Not until…的句型，我们知道考点为倒装句，答案在C，D 中选一个。
改写为正常语序为，Man did not know what heat is until the early years of the 19th. 现在将not提前，后面就不能再用否定了,否则意思就变了。