1. They couldn't help you because they were not here.
2. I can't go out because it is raining.
3. We haven't got any food, so we are going shopping.
4. There was fog, so their flight was delayed.
5. The film was boring, so we decided to go home.
6. I couldn't do this exercise, so I asked Tom for help.
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because + mệnh đề: bởi vì...
so + mệnh đề: nên...
