1. It began to rain, so we had to stay here.

2. My teacher asked me to go, so I went.

3. She was ill, so she didn't go to school.

4. Salt takes in plenty of water, so most bacteria can not live in a salty environment.

5. The floor is wet, so it is easy to fall down.

希望这些例子能帮助你理解"so"的用法。