定语从句用that而不用which的五种情况1、HYPERLINK"http://wenwen.soso.com/z/Search.e?sp=S%E5%85%88%E8%A1%8C%E8%AF%8D&ch=w.search.yjjlink&cid=w.search.yjjlink"\t"_blank"先行词为allmuchlittleeverythinganythingnothingnonefewtheone等HYPERLINK"http://wenwen.soso.com/z/Search.e?sp=S%E4%B8%8D%E5%AE%9A%E4%BB%A3%E8%AF%8D&ch=w.search.yjjlink&cid=w.search.yjjlink"\t"_blank"不定代词；例如：Imeantheonethatwasboughtyesterday.IsthereanythingthatIcandoforyou?Allthatcanbedonemustbedone.2、当先行词被形容词的最高级或序数词修饰，或被theonly,thevery,thesame,thelast,any,few,little,no,all,oneof等修饰时。例如：Thatisoneofthemostinterestingbooksthataresoldinthebookshop.Thefirstthingthatweshoulddoistogetsomefood.Mynecklaceisnottheonlythingthat'smissing.3、当主句以who或which开头时，定语从句中引导词用that,不用which或who。以避免重复。例如：Whoisthegirlthatiswearingaredcoat?4、当先行词既有人又有物时，用that。例如：Thewriterandhisnovelthatyouhavejusttalkedaboutarereallywellknown.5.先行词在主句中做HYPERLINK"http://wenwen.soso.com/z/Search.e?sp=S%E8%A1%A8%E8%AF%AD&ch=w.search.yjjlink&cid=w.search.yjjlink"\t"_blank"表语或HYPERLINK"http://wenwen.soso.com/z/Search.e?sp=S%E5%85%B3%E7%B3%BB%E4%BB%A3%E8%AF%8D&ch=w.search.yjjlink&cid=w.search.yjjlink"\t"_blank"关系代词在HYPERLINK"http://wenwen.soso.com/z/Search.e?sp=S%E4%BB%8E%E5%8F%A5&ch=w.search.yjjlink&cid=w.search.yjjlink"\t"_blank"从句中做表语时；It’sbookthatwillhelpyoualot.Myhometownisnolongtheplacethatitusedtobe.Heisnotthemanthatheusedtobe.