1,
→Because English is difficult, students learn it badly.
→ Because of the difficult English, students learn it badly.
2,
→ Because Miss Dung is very kind, many people like her.
→ Because of Miss Dung's kindness, many people like her.
3,
→ Because they didn't review the lesson carefully, they didn't do the test well.
→ Because of not reviewing the lesson carefully, they didn't do the test well.
−−−−−−−−−−
- Because + S + V, S + V
- Because of + V-ing, N/ N. Phrases, S + V