that可以引导名词性从句、定语从句。that引导名词性从句时（即主语、宾语、表语、同位语从句），在从句中无具体含义，只起连接作用，而且在从句中也不作任何句子成分。
扩展资料
that引导定语从句要注意以下几点：
1、定语从句中缺主语，修饰人时用who／that，修饰物时用which／that引导。如： Is this the factory which／that makes TV sets？The man who／that visited our school is from Australia．
2、从句中缺宾语，修饰人时用who／whom／that或省略引导词；修饰物时用which／that或省略引导词。如：Gone are the days which／that we spent together in the village．He is the man who／whom／that I think to be worthy of our praise.
