Here’s the rewrite of the sentences using double comparison:

1. Students become more and more nervous as they get closer to their exams.

2. The more cats I look after every day, the more expensive it becomes to supply cat food.

3. The more you write, the more fluent you’ll become.

4. The smaller computers get, the harder they are to afford.

5. The longer the days get, the more sunlight we’ll get.

6. The older people get, the more independent they become.

7. The less I spend, the more money I’ll save.

8. The more time you have, the more work you can do.

9. The more exams I have these days, the more tired and sleepless I get.

10. The more you travel, the better you will know the world.