倒装句
某些固定表述结构中，需要进行倒转。
规律1：否定副词/否定副词词组放置句首（never，seldom，rarely，scarcely ，hardly）
- I have never seen such a weird (奇怪)person once in my life.
- Never once in my life have I seen such a weird person .How can she go to the student's canteen（食堂） in pajama（睡衣）?
规律2 ：not only -- but also 结构中， not only 引导的句子要倒转（变成一般疑问句的形式）
- I not only saw him ,but also exchange some ideas with him
- not only did i see him , but also I exchanged some ideas with him
- 组动词提前
规律3： no sooner .. than ; hadly /scarcely...- 前倒后不倒 前过完 后过
- 翻译成 一... 就....
- no sooner had he heard the good news than the postman arrived
- 只要求了解，一般不考察
规律4：not until
- 前不倒后倒；前过完，后过
- not until the thief had had a chance to get away did the policeman arrive
- 只要求了解，一般不考察
- 正常语序 The policeman did not arrive until the thied had had a chance to get away
规律5:only 引导的成分作状语语句置句首
- 仅仅在大学毕业之后我才知道我什么都没学到
- Only after I had graduated from college did I know that I had not learned anything useful.
- 正常语序
- I knew that I had not learned anything useful only after I had graduated from college
- 经典写作句：Only in this way can we solve the problem.