1. His girlfriend will be introduced on his next birthday. ( Cấu trúc câu bị động: S+to be+ V past participle (+by O) )

2. She asked me when I would return the books to the library. ( Cấu trúc: S1+ asked/wanted to know/wondered/.. + wh+ S2 + ( would/might/could/should/had/... + V bare)

3. Unless you try hard will you pass the exam. ( Cấu trúc đảo ngữ Unless+ S+V+ aux V + S + Vbare)

4. I wish I had taken my doctor's advice. ( Cấu trúc câu ước: S+ wish + S+ V past/participle)

5. I don't know about it as much as she does.

6. Although my sister was tired, she helped me with my homework. 

1. He will introduce his girlfriend on his next birthday.

His girlfriend will be introduced on his next birthday

2. “ When will you return the books to the library?” she asked me

She asked me when I would return the book to the library.

3. If you don’t try hard, you will not pass your final exam

Unless you try hard, you will not pass your final exam

4. It’s a pity I didn’t take my doctor’s advice.

I wish I had taken my doctor's advice.

5. She knows a lot more about it than I do.

I don’t know as much about it as she does.

6. My sister was tired but she helped me with my homework.

Although my sister was tired, she helped me with my homework.