部分倒装是指将谓语的一部分如助动词或情态倒装至主语之前。如果句中的谓语没有助动词或情态动词，则需添加助动词do，does或did，并将其置于主语之前。
句首为否定或半否定的词语，如no，not，never，seldom，little，hardly，atnotime，innoway，notuntil…等。
Never have I seen such a per formance.
Now here will you find theanswer to this question.
Not until the child fell a sleep did the mother leave the room.
当Notuntil引出主从复合句，主句倒装，从句不倒装。
注意：如否定词不在句首不倒装。
I have never seen such a performance.
The mother didn't leave the room until the child fell a sleep.
典型例题
1）Why can't I smoke here？
At notime___inthemeeting-room
A.is smoking permitted B.smoking is permitted
C.smoking is it permitted D.does smoking permit
答案A.这是一个倒装问题。当否定词语置于句首以表示强调时，其句中的主谓须用倒装结构。这些否定词包括no，little，hardly，seldom，never，notonly，notuntil等。本题的正常语序是Smoking is permitted in the meeting-roomat notime.
2）Not until the early years of the 19thcentury___whatheat is.
A.mandid knowB.manknowC.didn't man knowD.did man know
答案D.看到Notuntil…的句型，我们知道为一倒装句，答案在C，D中选一个。
改写为正常语序为，Mandid 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。