代表物时多用which,但在带有下列词的句子中用that而不用which,这些词包括当先行词是anything,everything,nothing,none等不定代词时,或者是由every,any,all,some,no,little,few,much等修饰时等,这时的that常被省略还有先行词前有序数词或形容词最高级修饰时,或先行词就是序数词或最高级时.以及先行词中既有人又有物时.还有句中前面有which时,都只能用that

　　a)在不定代词,如：anything,nothing,everything,all,much,few,any,little等作先行词时,只用that,不用which.

　　Allthatisneededisasupplyofoil.

　　Finally,thethiefhandedeverythingthathehadstolentothepolice.

　　b)先行词有theonly,thevery,thejust修饰时,只用that.

　　Heistheverymanthathelpedthegirloutofthewater.

　　c)先行词为序数词(thelast)、数词、形容词最高级时,只用that.

　　ThefirstEnglishbookthatIreadwas"ThePrinceandthePauper"byMarkTwin.

　　d)先行词既有人,又有物时.

　　Hetalkedabouttheteachersandschoolsthathevisited.

　　e)当主句是以who或which开始的特殊疑问句时,用that以避免重复.

　　Whoisthepersonthatisstandingatthegate.

　　f)关系代词在从句中做表语

　　Heisnotthemanthatheusedtobe.