that必用1先行词是最高级或被最高级修饰2是序数词或被序数词修饰3不定代词指物5被only；the every，no，one of等修饰6主句有which；who；whom7there be 句型中8如果有两个从句，其中一个关系代词已用了which,另一个关系代词宜用that9先行词在主句中作表语，或者关系代词本身作从句的表语是宜用thatthat在作宾语时可省10.不是任何时刻关系词作主语宾语是能用that难点分析you.注意1：, the only，the same,the last ,any,little等修饰时(1) This is the very good dictionary ...
