凡是助动词/情态动词/系动词/谓语动词位于主语前面的句子，都可称为倒装句，助动词/情态动词/系动词提于主语前的为半倒装；谓语动词位于主语前的为全倒装。
英语中倒装一般是用来强调句子当中某一部分内容或者是为了文章句子结构衔接的需要而形成的。
例如：When did you arrive there?
Hardly can i move it.
He is very clever. So is she.
Here comes the bus!
等等...
谓语动词在主语之前
倒装句分为全部倒装和部分倒装。全部倒装即把谓语提到主语之前，部分倒装即把谓语动词中一部分提到主语之前。究其原由，一是语法需要，二是修辞需要。但在实际应用中，特别是在复合句中，学生常常分不清楚是在主句中倒装，还是在从句中倒装。下面就中学英语中的这种现象加以列举。
（一）在主句中倒装
1. not only…but also…连接两个对等成分时
Not only was everything he had taken away from him, but also his German citizenship.
Not only should we not be afraid of difficulties, but we should overcome them.
2. so…that… 结构中，强调so 所修饰的词时，句子倒装
So loudly did he speak that every one of the class could hear him.
So shallow is the lake that no fish can live in it .
3. hardly (scarcely) …when…,no sooner…than…结构中，强调否定意义的词时
Hardly had I reached the bus stop when the bus started.
No sooner had he arrived home than he was asked to start on another journey.
4. not until位于句首时
Not until all the fish died in the river did the villagers realized how serious the problem was.
5. 有时为了平衡句子
Gone are the days when we used“foreign oil”.
At last came the day when he was to be thrown to the prison.
（二）在从句中倒装
1. as引导的让步状语从句中倒装
Child as he was, he knows a great deal.
Disabled as Paul was, he went on serving the people.
2. 虚拟语气中，如从句谓语含were, had should，则省去if用倒装
Were I not working, I would be quite willing to do what you ask me to.
Had I known, I might have joined you in the discussion.
3. 介词+关系代词引导的定语从句中
They arrived at a farmhouse, in front of which sat a small boy
参考资料：http://zhidao.baidu.com/question/1221215.html
英语中的倒装句有部分倒装和完全倒装,比如以Only开头的就要倒装,
例如Only with hard work can you expect to get a pay rise.
这里的can you 就是个倒装形式..还有以否定开头的也要倒装..等等
谓语动词在主语之前
倒装句分为全部倒装和部分倒装。全部倒装即把谓语提到主语之前，部分倒装即把谓语动词中一部分提到主语之前。究其原由，一是语法需要，二是修辞需要。但在实际应用中，特别是在复合句中，学生常常分不清楚是在主句中倒装，还是在从句中倒装