besides此外

I am too tired to go; besides, it's too late.

我很累不能去，此外，天色也晚了。

hence因此

My mother is by herself; hence I must go home now.

我妈妈独自一人在家，因此我现在必须回去了。

meanwhile与此同时

Mother went shopping; meanwhile I cleaned the house.

母亲去购物，与此同时我打扫房间。

moreover此外

Bicycling is good exercise; moreover, it won't pollute the air.

骑自行车是一种很好的运动，此外，还不污染空气。

then此外，还有

I was there; then there were my mother and father.

我在那儿，此外，我的爸爸妈妈也在那儿。

therefore因此

I think; therefore I am.

我思故我在。

thus因此

It's late, and thus you must go.

天晚了，因此你必须走。

下面来看几个连接副词在作副词和连词时的区别：

However

however作副词时，可位于形容词/副词之前：

You couldn't earn much, however hard you worked.

无论你干得多卖力，你都挣不了多少钱。

however作连词时通常意为“但是”，可位于它所引导的从句之前或之后，或位于第一个词或短语之后：

I'll offer it to Tom. However, he may not want it. / He may not want it however. / Tom, however, may not want it.

我将提出把这个给汤姆，然而他可能不要它。

但提到两句意义相反的话时， however意为“但是/仍然/同样”：

They hadn't trained hard, however(/ but/ nevertheless/ all the same) they won.

他们并没有刻苦训练，但/无论如何/仍然/同样获胜了。