You use or to link two or more alternatives.
'Tea or coffee?' John asked.
“喝茶还是咖啡?” 约翰问。
He said he would try to write or call as soon as he reached the Canary Islands.
他说他一到加那利群岛就会尽快写信或打电话过来。
You use or to give another alternative, when the first alternative is introduced by 'either' or 'whether'.
Items like bread, milk, and meat were either unavailable or could be obtained only on the black market.
像面包、牛奶和肉这样的食品要么没有,要么只有在黑市上才能买到。
Either you can talk to him, or I will.
要么你和他谈,要么我来。
You use or between two numbers to indicate that you are giving an approximate amount.
Everyone benefited from limiting their intake of coffee to just one or two cups a day.
如果能控制住每天只喝一至两杯咖啡,那么对身体是有好处的。
When I was nine or ten someone explained to me that when you are grown up you have to work.
在我9岁或10岁的时候,有人对我说,人长大之后必须工作。
You use or to introduce a comment which corrects or modifies what you have just said.
The man was a fool, he thought, or at least incompetent.
他想,那人是个傻子,或者至少没什么能耐。
If you say that someone should do something or something bad will happen, you are warning them that if they do not do it, the bad thing will happen.
otherwise
She had to have the operation, or she would die.
她必须进行手术,否则会死的。
You use or to introduce something which is evidence for the truth of a statement you have just made.
He must have thought Jane was worth it or he wouldn't have wasted time on her, I suppose.
我想,他当时肯定认为简值得他费心思,否则他也不会在她身上浪费时间了。
or not
You use or not to emphasize that a particular thing makes no difference to what is going to happen.
Like it or not, you're in charge.
喜欢也好,不喜欢也罢,反正是你负责。
or no
You use or no between two occurrences of the same noun in order to say that whether something is true or not makes no difference to a situation.
The next day, rain or no rain, it was business as usual.
不管第二天下不下雨,一切照常进行。