先行词有the only，the very，the just修饰时，只用that.
He is the very man that helped the girl out of the water .，3，如果先行词是表示人的不定代词时，只能用who，否则都可以。用the only修饰物时，只能用that不能用which引导定语从句。，2，that
只能用that的情况
序数词、最高级、the very+名词、the only+名词、all之后等等，0，应该用that，0
the only先行词
the only做先行词时，后面关系代词用that.
例句：This is the only book that is worth reading.
