=>
1. It is not difficult to study Vietnamese.

-> It's (not) difficult to V : Thật (không) khó để
2. It is important to learn E.

-> It's important to V : thật quan trọng để
3. I am disappointed to get bad results in the final examination.

-> S be adj to V
4. I am very sad not to join the school football team.

-> S be adj not to V
5. It was very stupid of her to go out without a raincoat.

-> It was very stupid of her to V : Cô ấy thật ngu ngốc khi
6. It is wrong of him to break the rules of the school.

-> It is wrong of him to V : Anh ta đã sai khi
7. She is excited to get first prize in the competition.

-> S be adj to V
8. She is very surprised to hear that I had won a lottery.

-> S be adj to V
9. I am very happy to meet my long-lost friend again.

-> S be adj to V
10. It is interesting for Linda to study and listen to music at the same time.

-> be adj for sb to V
11. It is kind of Mary to help the poor and the disabled.

-> It is kind of Mary to V : Mary thật tốt bụng khi