1、当while, when, as引导时间状语从句时的区别：①while引导的状语从句中动词必须是持续性。谓语动词多为进行时，或状态动词的一般时。while 的这些用法可用when代替，等于 “at the time that”, “during the time that”。例如：Please keep quiet while (when) others are studying；② when除可指一段时间外，还可用来指一点时间，等于 “at the time”，也就是说when引出的时间状语从句中的谓语动词可以是终止性的，也可以延续性的。因此主句和从句的谓语可以是一般时，进行时，或完成时。例如：When I went into the lab, the teacher was doing an experiment.(when不能换成while)He often makes mistakes when he is speaking English.(when可换成while)③as常可与when，while通用，但强调“一边、一边”。例如：As (when, while) I was walking down the street, I noticed a police car in front of number 37. ④when引导的状语从句中的主语与主句主语一致，主、谓是“主语+系动词”结构时，这时主语和系动词可以省略。例如：When (he was) young, he worked for a rich man./ She’ll be here to give you help when (if it is) necessary. ⑤when有时代替if，引导条件句，意为“如果”、“假如”，例如：I’ll come when (if) I’m free.

46. The more you practise ______ English, the better your _____ English will be.

　　　 A. to speak, speaking　　　 B. speaking, spoken　 C. spoken, spoken　 D. spoken, speaking

语法复习十二：非谓语动词(一)--动词不定式

1~5 DDACC　 6~10 BCCAD　 11~15 CABAA　 16~20 BBAAB　 21~25 ADBAA

26~30 DBAAC　 31~35 DBBCD　 36~38 BBC

语法复习十二：非谓语动词(二)--动词-ing形式

1~5 CDDAB　 6~10 BAACB　 11~15 BCADC　 16~20 BCCDB　 21~25 CDDAD

26~30 DAAAB　 31~35 ABCBB　 36~40 CADDD

语法复习十二：非谓语动词(三)--过去分词

1~5 BCBBD　 6~10 CCBCB　 11~15 CDCBC　 16~20 ABAAC　 21~25 ADABA

26~30 ADBAD　 31~35 ACABC　 36~40 AABDD　 41~46 ABBBDB

45. Anna is often heard ______songs in her room.　　　　　　　　　　　　　　

　　　 A. sung　　　　　　　 B. singing　　　　　 C. sing　　　　　　　 D. to sing

44. I went ______a balloon but I didn't see anyone _____ balloons.

　　　 A. to buy, to sell　　　 B. to buy, selling　　　 C. buying, selling　　　 D. buying, to sell

43. This soup is cold; it needs _____.

　　　 A. to heat　　　　　　 B. to be heated　　　　 C. being hot　　　　　 D. heated

42. She sat at the desk and set about _____ a letter to her friend.

　　　 A. to write　　　　　　 B. writing　　　　　　 C. write　 　　　　　　D. written

41. Although swimming is his favourite sport, yet he doesn't like _____ today.

　　　 A. to swim　　　　　 B. swimming　　　　 C. swim　　　　　　 D. to have swim

40. No one was surprised at _____ the examination.

A. he passing　　　　 B. his pass　　　　　　 C. him pass　　　　　 D. his passing

39. Anna spends one hour a day _____ spoken English.

　　 A. practise　　　　　　 B. to practise　　　　　 C. on practising　　　 D. in practising

38. Dick made it ______ to all his friends.

　　 A. to know　　　　　 B. known　　　　　　 C. know　　　　　　 D. knowing