Ответ:

  1. The first television programmes were shown at the beginning of the 20th century.
  2. Nowadays new television technologies are being developed.
  3. He says the new book is being discussed in Room 15 now.
  4. Look! A new school is being built in our street.
  5. A lot of programmes on TV are devoted to sport.
  6. This fact is known to everybody.
  7. Don’t worry! Your papers are being prepared. They’ll be ready soon.
  8. These exercises were done yesterday.
  9. When Nick entered the kitchen, dinner was being cooked.
  10. These books are sold everywhere now.

Ответ: 1) were shown; 2) are being developed; 3) is being discussed; 4) is being built; 5) are devoted; 6) is known; 7) are being prepared; 8) were done; 9) was being cooked; 10) are sold.