5. It is necessary to learn English.
   => Learning English is necessary.

6. "How many people are there?" asked the journalist.
   => The journalist asked me how many people there were.

7. It was such rotten meat that it had to be thrown away.
   => The meat was so rotten that it had to be thrown away.

8. It is easy to ride a bike.
   => Riding a bike is easy.

9. You can't visit the USA unless you have a visa.
   => If you don't have a visa, you can't visit the USA.

10. "Can I borrow your typewriter, Janet?" asked Peter.
    => Peter asked Janet if he could borrow her typewriter.

11. She started working as a secretary five years ago.
    => She has been working as a secretary for five years.

12. She knows a lot more about it than I do.
    => I don't know as much about it as she does.

13. My French friend finds driving on the left difficult.
    => My French friend isn't used to driving on the left.

14. They water the flowers in the garden every day.
    => The flowers in the garden are watered every day.

15. We don't go on holiday because we do not have enough money.
    => If we had enough money, we would go on holiday.

16. The children couldn't go swimming because the sea was rough.
    => The sea was too rough for the children to go swimming.