=>
1. I can't help you because I'm very busy now.
2. He stayed at home last Friday because it rained heavily.
3. We turn on all fans because it is very hot.
4. The students learn English badly because it is very difficult.
5. Because Miss Dung is very kind, everyone likes her.
6. We can do the exercise quickly because they are very easy.
7. Because they didn't review the lesson carefully, they didn't do the test well.
