定从要学好，删繁就简系首要，明确先行词，然后定关系词调；

　　指人主格用who，宾格whom好，事物用which，主/宾都可靠；

　　用that引定从，人/物均需要，非限制性定从句，切勿用that导；

　　关系词作宾语，常将其省略掉，若介词+关系词，关系词切勿抛，无论人/事物，who/that均不导，指人必whom，事物which邀；

　　as引定从，（部分）主句内容包，常含“正如”意，位置任意挑；

　　which如此用，用时思量好，有时含“消极”味，主句之后到；

　　such/ the same + as，固定搭配好，特殊用法务牢记，勿用乱了套；

　　whose作定语，人/物它全包，n. + of + whom/which，可与其对调。

　　二、只用that作关系代词的几种情况

　　先行（词）本身系数词，不定代词指事物，

　　人与事物共先行，There be中指物词作主语，

　　关系词定从中作表语，问句避免疑问词重复，

　　另有序数词/最高级，every/ the very/ the only，

　　以及不定代词若干个，名词前把事物来修饰，

　　以上情况请记清，只能使用that引导定从句。

　　[巩固练习]

　　请在横线上添上恰当的关系词。

　　1. We need comrades _____________ can help us.

　　2. The man _____________ you saw yesterday was a doctor from Beijing.

　　3. This is a story about a communist fighter _____________ name或the name of _____________ is Liu Hu-lan.

　　4. This is our classroom， _____________ windows或the windows of _____________ face the south.

　　5. Here is a book _____________ will give a lot of useful knowledge.

　　6. This is the song _____________ we like best.

　　7. I will never forget the day， on _____________ I first saw him.

　　8. This is the room _____________ Lao Liu once lived in.

　　9. Do you still remember the day on _____________ he joined the army？

　　10. The earth， _____________ we all know， moves around the sun.

　　11. _____________ is known to all， the earth is round.

　　12. The sun is bigger than the earth， _____________ is known to us all.

　　13. He did not study hard， _____________ led to his failure.

　　14. We used the same type of machine _____________ they did.

　　15. We have found such materials _____________ are used in their factory.

　　16. Here are five fish. The two _____________were caught yesterday are gold fish.

　　17. Everything _____________ I told you just now is true.

　　18. They talked of the things and persons _____________ they remembered in the school.

　　19. There are stars _____________ we still don‘t know in space.

　　20. Li Ying is not the girl _____________ she used to be ten years ago.

　　[试题答案]

　　1. who/that    2. who/whom/that/×

　　3. whose； whom   4. whose； which

　　5. which/ that   6. which/ ×

　　7. which    8. that/which/ ×

　　9. which    10. as

　　11. As     12. as/ which

　　13. which    14. as

　　15. as     16. that

　　17. that/ ×    18. that/×

　　19. that/×    20. that