X.

1. It's important to keep the environment clean.

2. The time machine will be shown to the public when they finish it.

3. He was delighted that he received his aunt's letter.

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

5. I'm very sad not to be accepted in that group.

6. I haven'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 is Lan's fifteenth birthday next week.

10. When did you use the pen.

XI.

1. Minh has collected stamp since he was a child.

2. I am not working tomorrow so we can go somewhere.

3. They are going back to England in two months.

4. TV bringing not only information but also entertainment.

5. At home on the farm life is always a struggle with nature.

"Chúc bn học tốt"

X.

1. It's important to keep the environment clean

2. The time machine will be shown to the public when they finish it

3. He was delighted that he received his aunt's letter

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

5. I'm very sad not to be accepted in that group

6. I haven'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 is Lan's fifteenth birthday next week

10. When did you use the pen

XI.

1. Minh has collected stamp since he was a child

2. I am not working tomorrow so we can go somewhere

3. They are going back to England in two months

4. TV bringing not only information but also entertainment

5. At home on the farm life is always a struggle with nature

Answer by @Lucyvu2k8, do not copy!