Here are the rewritten sentences:

1. The Nile is the longest river in the world.
- No river is longer than the Nile.

2. We will probably visit Japan in the future.
- We might visit Japan in the future.

3. My brother can run very fast.
- My brother is very fast at running.

4. Nga likes badminton best.
- Badminton is Nga's favorite sport.

5. My children enjoy studying English very much.
- My children are very interested in studying English.

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**Task 6: Rewrite sentences:**

1. Unless we protect the environment, we will destroy ourselves.
- If we do not protect the environment, we will destroy ourselves.

2. Unless she is more hard-working, she will not get low marks.
- If she is not more hard-working, she will not get low marks.

3. Unless he listens to his parents, he will fail.
- If he does not listen to his parents, he will fail.

4. They began watching the movie one hour ago.
- They have been watching the movie for an hour.

5. He last cried ten years ago.
- He has not cried in ten years.

6. This is the first time he went abroad.
- He hasn’t gone abroad before.

7. She started driving one month ago.
- She has been driving for a month.

8. We began eating when it started to rain.
- We have been eating since it started to rain.

9. Nam likes watching television.
- Nam enjoys watching television.