or

1.关于He cannot read (n)or write等句，参见 nor 2

2.两个或两个以上的属于单数形式的名词，被or连接起来了，那动词必须是单数。例如：A man or a woman is waiting in the room. A man, a woman, or a boy is waiting in the room.和A man or a woman or a boy is waiting in the room.

3.注意下面各句里的斜体字：

• Were you or he there?
• Was he or you there?
• Either he or you were there.
• Either you or he was there.

但这种结构往往被避免使用，上面四句可以改作：

• Were you, or was he there?
• Was he, or were you there?
• Either he was there, or you were.
• Either you were there, or he was.

4.注意下面各句里的斜体字：

• A boy or a girl is preparing his or her lessons.
• A boy or a girl is preparing his lessons.
• A boy or a girl is preparing their lessons.
• Either a boy is preparing his lessons or a girl is preparing hers.

第一句不自然，第二句不正确，第三句不合语法，第四句不简洁。这种句子最好避免。在不能避免的时候还是用第一句或第四句的好。

5.可以说Paul had to obey his boss or resign。His boss is the kind of man Paul had to obey or resign里的or resign在语法上讲不通，但合乎习惯。

6.比较下面三句：

• Put on more clothes, or you may catch cold.
• I told him that he should put on more clothes, or he might catch cold.
• I told him to put on more clothes, or he might catch cold.

第二句和第三句不及第一句合理，但都可以说。