连词是连接单词，短语或从句的语法连接符。 连词可以表示它在句子中连接的元素之间的关系。 没有这些，我们就不会看到这种关系。 连词有三种类型：并列，相关和从属。
并列连词具有相同或相同语法功能的单词，短语和子句。 协调连词包括： and, but, or, yet, nor, for, and so.
- 连接名词: I will buy a coat and a hat.
- 连接动词: I did not call nor write my mother.
- Connecting adjectives: The boy was nice but weird.
- Connecting dependent clauses: If the students show up and the teacher is prepared, class will be productive.
- Connecting independent clauses: Ten thousand students applied to the college, but only six thousand were admitted.
相关联合是一种协调连接，它成对地连接句子中的元素。 相关的连词包括： both...and, not...but, not only...but also, either...or, neither...nor, although...yet, whether...or.
- Connecting nouns: The name of the store is not Food World but Food Land.
- Connecting adjectives: The place of employment shall provide both health and life insurance.
- Connecting prepositional phrases: Orange juice is made either by squeezing oranges or by mixing a can of frozen concentrate.
- Connecting independent clauses: Not only did the cat jump over the fence, but he also scratched the paint.
从属连接将具有不同语法功能的元素连接起来，通常是依赖和独立的子句。 从属连词包括： after, in case, unless, although, in that, until, as, now that, when, as if, once, whenever, as though, since, where, because, so, whereas, before, so that, whether, even though, than, which, except that, that, while, however, though, who/whom, if.
- He acts as though he has done something wrong.
- I am sure that the teacher will let class out early.
- When the bell rings, the students must sit down.
- Since the cat ran away, the girl has been sad.