adv. 因此；所以；故；乃
therefore有两种用法,一在整句中,一在分句中.therefore是副词,但有时具有连词作用.
一、整句中时一般不放句末,句首后要有逗号,句中1、按一般副词使用2、做插入语（这两个分得清吧）
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,即一个句子一部分表示原因一部分表示结果.
这时一般词前要用分号,其后用不用逗号无所谓.若第二个分句前是逗号或无符号,则要注意therefore是副词,和so不一样,要保持句子完整,应用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.
1. The truth is that junk bonds were misnamed, and therefore misunderstood.
事实上人们对垃圾债券的称谓有误，所以产生了误解。
2. They had seen him trawling and therefore knew that there were fish.
他们曾见过他用拖网捕鱼，因此知道那里有鱼。
3. Men are anxious to improve their circumstances, but are unwilling to improve themselves; they therefore remain bound.--James Allen
人们总是渴望改善周遭环境，但是却不愿意改善自己，因此总停留在原地，无法进步。
4. He's only 17 and therefore not eligible to vote.
他只有17岁，因此没有投票选举的资格。
5. He lost his health, and therefore his difficulties increased.
他身体虚弱, 因此更增加了他的困难.
6. The Chinese Christians, therefore, practically excommunicate themselves from their own clan.
所以, 中国的基督徒简直是被逐出了自己的家族了.