什么情况用完全倒装句,什么情况用不完全倒装句?

其实英语没有那么固定的句式，很多根据语境来的，建议你多看一些美剧（必须要带字幕的），会很快提高你的语感和词汇量。你若要是真想问出个所以然来请看天下文章一大抄：
1. “某些副词+不及物动词+主语”的句式，需要全部倒装。常用的副词主要有：here , there , now , then , out , in , down , up , away 等，表示强调。主语是代词时，不必倒装。
Out rushed the boy .
　　Down came the brown wave .
　　2. 表示方位的短语放在句首，后面一般使用倒装语序。
　　West of the lake lies the famous city .
　　3. There be + 主语+地点。其中动词be也可以是其他词，如lie，stand等。
　　There are many different kinds of mooncakes on the table .
　　There in Greece lived a famous thinker , named Aristotle .
　　4. 如果直接引语后注明是什么人说的，而且主语是名词时，需要完全倒装；主语是代词时，一般不用倒装。
　　“Let’s go ! ”said the captain .
　　“Take off your boots !” ordered the guard .
　　5. 为了保持句子平衡，或为了强调表语或状语，或使上下文紧密衔接时。
　　They arrived at an old church , in front of which stood a big crowd of people .
　　6. 用于so开头的句子，表示重复前面相同的内容，意为“也怎么样”。另外，在结果状语从句句型so …that …中，如果强调so…放在句首，主句需要部分倒装。
　　I often go out for a walk after supper . So does she .
　　我经常在晚饭后出去散步，她也这样。
　　So excited was she at the news that she couldn’t say a word .
　　听到这个消息，她是如此激动，以致于一句话也说不出来。
　　7. 用于nor , neither 开头的句子，表示重复前面相同的内容，“也不怎么样”。
　　Li Lei can’t answer the question . Neither can I .
　　If you don’t wait for him , nor shall I .
　　8. only放在句首，强调状语（副词，介词短语或状语从句等），全句语序要部分倒装。
　　Only in this way can we get in touch with them .
　　Only because he was ill was he absent from school .
　　注意：only放在句首，强调主语时，语序不必倒装。
　　Only Mr Wang knows about it .
　　9. 带有否定意义的词放在句首，语序需要部分倒装。常见的词语有： not , never , seldom , scarcely , barely , little , at no time , not only , not once , under on condition , hardly … when , no sooner …than ……等。
　　Little did I think he is a spy .
　　我一点也没想到他是一个间谍。
　　Hardly had I reached home when it began to rain .
　　No sooner had I entered the room than the phone rang .
　　10. 在虚拟语气中，倒装代替条件。
　　Should he be here next week , he would help us with the problem .
　　Were there no light , we could see nothing .
　　11. 用于某些表示祝愿的句子。
　　May you succeed ! 祝你成功！ Long live France ! 法兰西万岁！

常见的完全倒装结构
1．there be 句型.
There is a mobile phone and some books on the desk.桌上有一个手机和一些书.
引导词there 还可以接appear,exist,lie,remain,seem,stand,live 等词.
There lived an old fisherman in the village.村里住着一位老渔夫.
2．用于here,there,now,thus,then + 动词 + 主语的句型中（谓语动词多为be,go,come等）.
Here comes the bus．汽车来了.
3．以out,in,up,down,off,away等副词开头,谓语动词是表示“移动”的go,come,leave等句子里.
Down fell the leaves.树叶掉了下来.
在完全倒装的结构里,如果主语是人称代词,则用正常语序.
Here we are.我们到了.
4．表示地点的介词词组位于句首,谓语动词是表示“存在”之意的be,lie,stand,exist等句子中.
South of the lake lies a big supermarket.湖泊的南边是一个大超市.
5.“表语+连系动词+主语”结构.
Gone are the days when he was looked down upon.
他被人看不起的日子一去不复返了.
常见的部分倒装结构
1.含有否定意义的副词或连词（如not,seldom,little,hardly,never,rarely,nowhere等）放在句首时.
I have never seen him before.
——Never have I seen him before.
——Never before have I seen him.我以前没见过他.
表示“刚……就……的倒装结构
Hardly had he started to leave when it began to rain.他刚要离开,天就下起了雨.
No sooner had he handed in his paper than he realized his mistakes.他刚交卷就意识到出错了.
2.副词only +状语放在句首时.
Only then did I see life was not easy.只有那时我才知道生活是不易的.
3.so作“也”讲时,引导的句子用倒装语序,表示前面所说的肯定情况也适用于另一人(或物).其句型是：So + be（have,助动词或情态动词）+主语.
She has been to Tokyo.So have I.她去过东京,我也去过.
如果对前面所说的内容,加以肯定,或不作“也”讲而只起连词作用,表示一种结果的意思,那不倒装.
--- Jack won the first prize in the contest.杰克在比赛中获一等奖.
--- So he did.确实是的.
4．Neither nor引导的句子用倒装语序,用于对前面所说的否定内容表示同样的看法.
She wo’t go.NeitherNor will I.她不走,我也不.
如果前面所说的内容既有肯定又有否定,或前后的谓语动词形式不一致时,用“It is the same with +主语”结构或用“So it is with +主语”结构.
He worked hard,but didn't pass the exam.So it was with his sister.他很努力,但没有通过考试.他妹妹也是这样.（既有肯定又有否定）
5.“so...that...和“such...that...”结构中的so或such位于句首时.
He was so excited that he could not say a word.
——So excited was he that he could not say a word.他如此激动以至于一句话都说不出来.
6．一些表示频率的副词（如many a time,often等）位于句首时.
Many a time have I seen her taking a walk alone.我多次看到她独自一人在散步.
7．表示方式、程度的副词位于句首时.
Gladly would I accept your proposal.我很高兴接受你的建议.
8．非谓语动词 + be + 主语.
Covering much of the earth's surface is a blanket of water.覆盖地球大部分表面的是水.