that在限制性定語從句中既可指人又可指事或物。在下列情況下，只能用that來引導定語從句：
1.先行詞被all,few,little,much,every,some,no等詞修飾或被theonly,thevery,thesame,thelast等限定詞修飾時。例如：
TheseareallthepicturesthatIhaveseen.
Thisistheverydictionarythatisofgreathelp.
2.先行詞是all,much,few,little,everything,anything,nothing等不定代詞時。例如：
Isthereanythingthatyouwanttobuy?
3.先行詞既指人又指物時。例如：
Myfatherandhisteachertalkedalotaboutthethingsandthepersonsthattheycouldremember.
4主句是who或which引導的特殊問句時。例如：
Whoisthegirlthatisstandingunderthetree?
WhichisthemachinethatweusedlastSunday?
5.先行詞被形容詞最高階或序數詞修飾時。例如：
ThisisthebestEnglishfilmthatIhaveeverseen.
ThefirstEnglishnovelthatIreadwasATaleofTwoCities.
6.關係代詞在定語從句中作表語時。例如：
Ourschoolisnottheonethatitusedtobe
that在限制性定語從句中既可指人又可指事或物。在下列情況下，只能用that來引導定語從句：
1.先行詞被all,few,little,much,every,some,no等詞修飾或被theonly,thevery,thesame,thelast等限定詞修飾時。例如：
TheseareallthepicturesthatIhaveseen.
Thisistheverydictionarythatisofgreathelp.
2.先行詞是all,much,few,little,everything,anything,nothing等不定代詞時。例如：
Isthereanythingthatyouwanttobuy?
3.先行詞既指人又指物時。例如：
Myfatherandhisteachertalkedalotaboutthethingsandthepersonsthattheycouldremember.
4主句是who或which引導的特殊問句時。例如：
Whoisthegirlthatisstandingunderthetree?
WhichisthemachinethatweusedlastSunday?
5.先行詞被形容詞最高階或序數詞修飾時。例如：
ThisisthebestEnglishfilmthatIhaveeverseen.
ThefirstEnglishnovelthatIreadwasATaleofTwoCities.
6.關係代詞在定語從句中作表語時。例如：
Ourschoolisnottheonethatitusedtobe