The people that lived here is a dentist.
(2)当先行词是两个或两个以上的人或物,用that
(3)当先行词是all,much,many,little,something,anything,eveything,nothing,none等词时,只用that
(4)先行词是系动词be后边的表语或关系代词本身是从句中的表语时,用that
This is a song that will be popular soon.
(5)主句用there be句型开头时,主语若指物,多用that
There is a position in the car that is still free.
(6)当先行词是最高级形容词或被最高级形容词修饰时用that
The third university that we visited is Beijing University.
(8)当先行词被very,only,one of,any,all,no,little,few等修饰时
(9)以who/which开头的句子中为避免重复,用that.