例句：
Therefore, as a result, so, then, consequently
She was therefore unable to find a solution. So she had to quit her job. I think; therefore I am.：我思故我在‘We have missed the train.’ ‘Then we are going to have to hire a taxi.’They grew up in Japan; hence their interest in Zen Buddhism.He sustained severe injuries and, consequently, spent the rest of his life in a wheel chair.Therefore is common in mathematical proofs.#比较正式，推荐在大多时候使用
Hence and thus#基本可以互换，hence多指未来或者接下来，hence 接will比较合适； thus用在过去式叙述中，重在结论
Hence and thus have the same basic meaning and are often interchangeable. However, there is a slight difference. Hence usually refers to the future. Thus usually refers to the past. It is often used to indicate a conclusion.
Both sides played well, thus no winner was declared.The situation is getting more and more complicated. Hence we will have to proceed with caution. (NOT Thus we will have to proceed with caution.)So and then# so比较通用，可以替代then，因此建议多用so，then用来指代两个人的response情况。 There is a difference between then and so. Then is used when one speaker replies to another. So can be used in both ways.
‘The last bus has gone.’ ‘So/ then we will have to walk.’ (Two speakers)‘The last bus has gone, so we will have to walk. (NOT ‘The last bus has gone, then we will have to walk’) (Same speaker)