1 "but" 和 "yet" 用来显示两个意思之间的对比关系。在写作中，当 "but" 和"yet" 将两个分句连为一个句子时，逗号就置于它们之前。它们也可以将两个单独句子的意思连接起来。
Transworld express promises next-day service, yet(but) I've never recevied anything on time from them.
Transworld express promises next-day service. Yet(But) I've never recevied anything on time from them.
2 "although"、 "though" 和 "even though" 用来将两个单独的句子连接成一个句子，并形成对照。在写作中，当这些词位于句首时，两个分句之间必须有逗号。当这些词位于第二个分句的开头时，则不用逗号。
Altough(Though, Even though) Dubois thinks the men's line is a risk, I think it's going to be successful.
Dubois thinks the men's line is a risk altough(though, even though) I think it's going to be successful.
3 "however" 用来显示意思之间的对比关系。"however" 可以置于第二个分句的不同位置，显示两个句子意思之间的对比关系。在写作中，通常用逗号将 "however" 与句子的其余部分分开。
Dubois thinks the men's line is a risk. However, I think it's going to be successful.
Dubois thinks the men's line is a risk. I, however, think it's going to be successful.
Dubois thinks the men's line is a risk. I think it's going to be successful, however.
4 "though" 通常将两个句子连接为一个句子。但是，在句中时可以用"however" 来替换。这种情形下，"though/however" 出现在 "I" 之后，这是因为说话者正在表明她和 Dubois 之间的不同。注意要用逗号将 "though/however" 与句子的其余部分分开。
Dubois thinks the men's line is a risk. I, though(however), think it's going to be successful.
5 在这个例子中，注意第二个句尾的 "though" 可以用 "however" 来代替。然后用逗号将其与句子的其余部分分开。
Dubois thinks the men's line is a risk. I think it's going to be successful, though(however).