一、联合关系
常用的连词有and(同，和), when(=and just at this time就在这时，然后), not only…but (also)…(不仅……而且……), neither…nor…(既不……也不……)等。如：
He helps me and I help him.他帮我，我帮他。
He not only gave us a lot of advice, but also helped us to study English. 他不仅给我们出很多建议并且还帮助我学英语。
I was just leaving when the telephone rang. 我正要离开，电话铃响了。
注：when作这种用法时，主要用于was/were doing sth. when sth./sb. did; was/were about to do sth. when sth./sb. did; was/were on the point of doing sth. when sth./sb. did等句型中，表示“当某人或某物正在或正要做某事，就在这时突然又发生了另一事”。
二、选择关系
常用的连词有or(或者，否则), otherwise(否则), or else(否则), either...or(不是……就是)。如：
Hurry up, or (else) you’ll be late. 快点，否则就会迟到了。
Will he still be there or will he have gone away? 你那时还在那里还是可能已经走了?
You must go early, otherwise you will miss the bus. 你好得早点走，否则就赶不上公共汽车了。
Either Tom is coming or his sisters are. 不是汤姆就是她的姐妹们要来。
三、转折关系
常用的连词有but(但是，可是，只是因为), while(而、却), yet(可是)等。如：
It never rains but it pours. 祸不单行。
I like tea while she likes coffee. 我喜欢喝茶而她喜欢喝咖啡。
She said she would be late, yet she arrived on time. 她说她会迟到，但她却准时到达了。
She looks very young, but she is already in her 30’s. 她看上去很年轻,可是她已三十多岁了。
此处，还有副still(仍然)，however(然而)也表示转折关系。
He is good-natured; still I don’t like him. 他脾气很好,可是我还是不喜欢他。
The book is expensive; however, it’s worth it. 这本书很贵;却很值。
注意：but, while不与although连用，但yet, still可与although连用。
Although she felt ill, she still went to work. 她虽然感觉不舒服，但她仍然去上班。
四、因果关系
常用的连词有for(因为)和so(所以，因此)等。如：
I am thirsty, for it is hot. 我口渴，因为天气太热。
The manager was ill so I went in her place. 经理病了所以我代她去。
注意：so不与because连用。
