1. 表示因果，如：therefore, hence, because, so, as, as aresult, consequently, since等。
- He's only 17 and therefore not eligible to vote.
2. 表示转折，如：however, but, though, even though, despite等。
- She has the window open, however cold it is outside.
3. 并列关系，如：and, also, too, as well as, either...or..., both...and..., meanwhile, at the same time 等。
- The mind needs exercise as well as the body.
4. 表示递进，如：furthermore, also, as well, too, in addition, moreover, besides, even, additionally 等。
- He said he had not discussed the matter with her. Furthermore, he had not even contacted her.
5. 表示顺序，如：first, second, third等。
- First, interest rates may take longer to fall than is hoped. Second, in real terms, lending may fall. Third, bad loans could wipe out much of any improvement.
