therefore有兩種用法,一在整句中,一在分句中.therefore是副詞,但有時(shí)具有連詞作用.

一、整句中時(shí)一般不放句末,句首后要有逗號,句中1、按一般副詞使用2、做插入語（這兩個(gè)分得清吧）

eg.1、Therefore,we must learn English well.

2、They therefore can learn English well.

3、Many fast food restaurant ,therefore,have red furniture or walls.

二、用在分句中,即一個(gè)句子一部分表示原因一部分表示結(jié)果.

這時(shí)一般詞前要用分號,其后用不用逗號無所謂.若第二個(gè)分句前是逗號或無符號,則要注意therefore是副詞,和so不一樣,要保持句子完整,應(yīng)用and therefore.

eg.1、I had a headache;therefore I could not go to your party.

2、I was ill,and therefore could not come.

3、These birds are very beautiful and therefore liked by many people.