"因为下雨，所以我没出门"写成 Because it rained, so I didn't go，老师就圈了。because 和 so 不能同时出现在一句话里。
and：并列、顺承
- I like apples and bananas.
- He got up, and washed his face.
but：转折
- I want to go, but I'm busy.
- She is young, but knows a lot.
so：所以
- It was late, so I went home.
- It's raining, so we stay inside.
because：因为
- I stayed home because it rained.
- He was late because he missed the bus.
两个铁律
because 和 so 不能同句出现：
- 对：Because it rained, I stayed. / It rained, so I stayed.
although 和 but 不能同句出现：
- 对：Although he is rich, he is unhappy. / He is rich, but he is unhappy.
or：否则
- Hurry up, or you'll be late. 快点，否则迟到了。
口诀：and 并 but 转，so 果 because 因；因为所以不相见，虽然但是不同框。
