The teacher said: '' I'm pleased that you study hard."

→The teacher told them that she was pleased that they studied hard.

Lời giải chi tiết: 

-  Đây là câu gián tiếp 

→ Động từ phải lùi thì: 

am⇒was

study ⇒ studied 

→ Phải đổi ngôi:

I⇒he/she

You⇒ They

The teacher told them he was pleased that they studied hard .

- Tường thuật trong câu gián tiếp: S + told/said to + smb + S + V(lùi thì)

- Thì HTĐ lùi thì thành thì QKĐ 

- QKĐ (V thường) : S + V2+ O

- QKĐ (V be): S + were/was + O .