这样理解完全正确.

　　定语从句中关系代词用that（不用which）的情况：

　　1.先行词是all,anything,everything,nothing等,关系代词应用that

　　That'sallthathetoldme.

　　2.先行词前有theonly,thesame,thevery或no,little,much,any,every,all等修饰时,关系代词应用that

　　SheistheonlypersonthatIknowinthiscompany.

　　3.先行词前有序数词或形容词最高级修饰时,关系代词常用that

　　ThefirstthingthatIwanttodoistotakeitaway.

　　4.当先行词同时含有"人"或"物"时,关系代词应用that

　　5.在固定结构thesame...that...;so...that...;such...that...以及itis/was...that...的强调句型中,要用that

　　Thisisthesameparkthatweoncevisited.

　　6.如主句以therebe开头时,关系代词应用that

　　Thereisaroomthathastwowindows.

　　希望能帮到你,祝你开心.