@dominic.jackson,

When you use 还是, you usually don't know about the situation. Therefore, 还是 is usually used in questions or sentences starting with 我不知道 (I don't know)，我没想好 (I haven't thought through) or 我没决定 (I haven't decided). For instance: 你想去北京还是去上海？(Do you want to go to Beijing or Shanghai?) or 我不知道去北京还是去上海 (I don't know if I'm going to Beijing or Shanghai).

When you use 或者, you are telling people several possibilities, so 或者 can not be used in questions. For instance, 我想去北京或者去上海 (I'm thinking about going to Beijing or Shanghai).

Also, there is a special usage of 还是. It can be used to tell people what your choice made after consideration. For example: A: 你想去北京还是去上海？ B: 还是去北京吧.

--Echo

echo@popupchinese.com