Ответ:

Christmas is celebrated on the 25th of December in Europe.

Apple was founded by Steve Jobs and Steve Wozniak in 1976.

Our managers will be invited to a meeting by them next month

The final exams will be taken by students in summer.

Some economic problems have been discussed by politicians at the meeting.

Branches of our company can be found  in most countries.

The contract with Barcelona has been signed by  Lionel Messi.

Fashionable clothes were made by Christian Dior

The president is elected every six years in Russia

New schools will be built by the government in the new districts of our city

A long interview is being given the newspaper reporters by the scientists now.

Ответ:

1. Christmas is celebrated by people is Europe on the 25th of December.

2. "Apple" was founded in 1976 by Steve Jobs and Steve Wosniak.

3. Our managers will be invited to a meeting next month.

4. The final exams will be taken by students in summer.

5.Some economic problems will be discussed at the meeting.

6. Branches of our company can be founded by you in most countries.

7. The contract with Barcelona club has been signed by Leonel Messi.

8. The teacher was followed by five or six small children.

9. Fashionable clothes made by Christian Dior.

10. The president is elected by people in Russia.

11. New school will be built by the government in the new districts of our city.

12. A long interview is given by scientists to a newspaper reporters.

Надеюсь, что все правильно. Удачи со сдачей! :3