一、改变时态

　　例:The bell is ringing now. 一般

　　There goes the bell.特殊

　　二、改变语态

　　例: People suggest that the conference be put off.一般

　　It is suggested that the conference be put off.特殊

　　三、使用不定式

　　例: He is so kind that he can help me.一般

　　He is so kind as to help me. 特殊

　　四、使用过去分词

　　例: 1 She walked out of the lab and many students followed her.一般

　　Followed by many students, she walked out of the lab.特殊

　　2 Once it is seen, it can never be forgotten.一般

　　Once seen, it can never be forgotten. 特殊

　　五、使用 v- ing

　　1 When he arrives，please give me an e-mail．一般

　　On arriving /his arrival ,please give me an e-mail.特殊

　　2 If the weather permits ,I will come tomorrow.一般

　　I will come tomorrow, weather permitting. .特殊