1) 当表示否定或基本否定的词或词组位于句首作状语时用倒装。这类词或词组常用的有：never, nowhere, seldom, rarely, little, hardly, scarcely, barely, not until, not only, by no means, in no time, under no circumstances, under no condition, in no way, in no case, at no time, on no account等。
Never have I heard it before.
Nowhere can I find my lost watch.
Under no circumstance should a student cheat in the exam.
Not only was Churchill a statesman, but also a poet.
Note: 当 “no sooner … than”和“hardly/scarcely … when/before”位于句首时用倒装。该结构表示“一…就…”，在时态上主句一般用过去完成时，when或than引导的从句用一般过去时。
Hardly/Scarcely had I got home when/before the bell rang.
No sooner had the performance begun than the lights went out.
2) 当here, there, then, thus, only, hence, little等副词位于句首，句中主、谓用倒装。
Here is the book for you.
There goes the bell.
Then came the order to take off.
Thus arose the division between the developed and developing countries.
3) 当 “so/such … that”结构中的so或such 位于句首时用倒装。
So cold was it at night that I could hardly fall asleep.
Such was the force of explosion that all the windows were broken.
4) 分句以so, neither, nor, no more等副词位于句首，表明前面句子中所说明的情况也使用于后面的句子时用倒装。
Copper is a good conductor. So are many other metals.
He didn’t see the film last night, neither did she.
这里讲的强调句主要是以it为引导词的分裂句。其构成形式为：It is (was) +被强调部分+ that(who, which) + 句子的其他部分。被强调的部分通常为主语、宾语和状语。
It is only when one is ill that one realizes the value of health.
It is what you will do that is essential.