1, It's very inportant to keep the environment clean

2, The time machine will be shown to the public when it is finished

3, He was delighted that his aunt sent him a letter

4, People recycle old car tires to make shoes and sandals

5, m very sad not to be accepted in that group

6, Thaven't spoken to her for three years

7, Tam used to type faster than she does now

8, My father asked me to turn down the radio for him

9, It's Lan fifteenth birthday next week

10, When did you use the pen?

II. Rewrite the sentence without changing the meaning 
1. Keeping the environment clean is very important.
- It’s …very important to keep the enviroment clean …………………………………………………………………………..
2. They will show the time machine to the public when they finish it. 
- The time machine ……will be shown to the public when they finished it  ……………….
3. He was delighted to receive his aunt’s letter.
- He was delighted that ……his aunt sent him letter…………………………………………………………..
4. Old car tires are recycled to make shoes and sandals.
- People ……recycle old car tires to make shoes and sandals ……………….
5. I’m very sad that I wasn’t accepted in that group.
- I’m very sad not ……to be accepted in that group……………………………………………………………….
6. It’s three years since I last spoke to her.
- I haven’t ……spoken to her for 3 years…………………………………………………………………………
7. Tam doesn’t type as fast as she used to.
- Tam used ………to type faster than she does now……………………………………………………………………..
8. It was such an interesting film that we watched it several times
- The film…………was so interesting that we watched it several times ………………………………………………
9. Peter was too ill to get up.
- Peter was so……ill that he can't get up……………………………………………………………
10. How long is it since you used the pen?
- When ………did you last use the pen………………………………………………………………….?