1. This novel is long enough to take me several weeks to read. This novel is so long that i spend several weeks reading it.

2. How long is it since he learnt French? → When did he started learning French?

3. I study English so that I can improve my knowledge →I study English so as to improve my knowledge 

4. They have given her a bunch of flowers. A bunch of flowers has been given to her 

5. Have you gone to school late before? → Is this the first time you went to school late?

6. He was delighted to receive his aunt's letter. > He was delighted that he received his aunt's letter. 7. He speaks more persuasively than his brother. → He is a more persuasive speaker than his brother. 

8. Lan forgot her birthday and so did 1. I didn t remember lan's birthday.

9He'd rather play gull than tennis. - He prefers playing gull to playing tennis

10. Mai broke the cup because of her carelessness. Mai broke the cup because she was careless

=>
1. This novel is so long that it takes me several weeks to read.
2. When did he start learning English?
3. I study English so as to improve my knowledge.
4. A bunch of flowers has been given her.
5. Is this the first time you have gone to school late?
6. He was delighted that he received his aunt's letter.
7. He is a more persuasive speaker than his brother is.
8. Lan didn't remember her birthday and neither did I.
9. He prefers playing golf to playing tennis.
10. Because Mai was careless, she broke the cup.