定语从句中：只用that而不用which的五种情况引导定语从句的关系代词有：that（指人或物）,which（指物）,who(指人）.指人时可用that或who；指物时可用that或which；但有时只能用that,不能用which.常见的情况有下列五种：1、当先行词是：all,any,anything,everything,nothing或被它们修饰时.例如：IsthereanythingthatIcandoforyou?有什么可以为你做的吗?Allthatcanbedonemustbedone.凡是能做的都必须做.2、当先行词被形容词的最高级或序数词修饰时.例如：Thatisoneofthemostinterestingbooksthataresoldinthebookshop.那是这家书店出售的最有趣的书之一.Thefirstthingthatweshoulddoistogetsomefood.我们该做的第一件事是弄点吃的.3、当先行词有：theonly,thevery,thesame,thelast等修饰时.例如：Mynecklaceisnottheonlythingthat'smissing.我的项链不仅是丢掉的东西.4、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?正穿一件红色外套的女孩子是谁?5、当先行词既有人又有物时,用that.例如：Thewriterandhisnovelthatyouhavejusttalkedaboutarereallywellknown.你刚才谈起的那位作家以及他的小说确实很著名.