` 1. ` It is interesting and helpful to learn the history, culture and development of the country's 54 ethnic groups

` - ` It + tobe + adj + and + adj + to V: Nó như thế nào và thế nào để làm gì

` - ` ` = ` S + find ( tùy thì ) + V - ing: Ai đó thấy việc gì đó như thế nào

` 2. To teach our students how to use the library is essential in my opinion

` - ` V - ing hoặc to V đứng đầu làm chủ ngữ

` - ` How to + V - inf: Cách làm gì

` - ` be + adj

` - ` Essential ( adj ): Thiết yếu

` - ` Should + V - inf: Nên làm gì

` # ` ` Ka `

`1`. It is interesting and helpful to learn about the history, culture and development of the country's `54` ethnic gouprs.

`->` It is + adj + to-V

`2`. To teach our students how to use the library is essential in my opinion.

`->` To-V + be + adj + in one's opinion