定語從句定義：1.定語：修飾或限制名詞，代詞用的。Heisourfriend.Thegirlbehindthetreeiskate.2.定語從句：在英語中，修飾名詞或代詞的句子叫做定語從句。Thegirlwhoisbehindthetreeiskate.定語從句分三步：1.先找先行詞2.看先行詞在句子中充當(dāng)?shù)某煞?.選擇適當(dāng)?shù)年P(guān)系詞3.定語從句修飾或限定的名詞叫做先行詞。4.引導(dǎo)定語從句的關(guān)聯(lián)詞成為關(guān)系詞。關(guān)系詞：｛關(guān)系代詞和關(guān)系副詞｝5.關(guān)系代詞有：whowhomwhosewhichthat6.關(guān)系副詞有：whenwherewhy二．關(guān)系代詞引導(dǎo)的定語從句關(guān)系代詞who、whom,that,which,whose所代替的先行詞是人或物。在句中作主語。賓語。表語等如果先行詞是人：who（主語。賓語）whom（賓語）that（主語，賓語）Heisthemanwho/thatwantstoseeyou.(主語)Heisthemanwho/whom/thatIsawyesterday.(賓語)如果先行詞是物：用which,thatThesearethebookswhich/thatheboughtwhenhewasyoung.whose在句中作定語，表示物主關(guān)系Isawawomanwhosebagwasstolen.關(guān)系副詞引導(dǎo)的定語從句關(guān)系副詞whenwherewhy在句中作狀語when代替的先行詞是時間，在句中作時間狀語。IstillrememberthedaywhenIfirstcametothisschoolwhere代替的先行詞是地點(diǎn)，在句中做地點(diǎn)狀語。BeijingistheplacewhereIwasborn.why代替的先行詞是原因，在句中作原因狀語。Doyouknowthereasonwhyshewaslate.四.只用that不用which的情況1，當(dāng)先行詞是不定代詞或有不定代詞修飾時HaveyoutakendowneverythingthatMrlihassaid?Ihavesomebooksthatareworthreading.2.當(dāng)先行詞是序數(shù)詞。形容詞最高級或被修數(shù)次，形容詞最高級修飾時ThebookisthebestthatIhaveread.3.當(dāng)先行詞前有thevery,theonly等修飾時ThisistheverygooddictionarythatIwanttobuy.4，當(dāng)主句已出現(xiàn)which時WhichistheT-shirtthatfitsmemost?當(dāng)先行詞既有指人的名詞又有指物的名詞時C