Ответ:

Solution:

  1. If we drove (drive) more slowly, we would save (not use) so much petrol.
  2. If we only bought (buy) the food we needed, we wouldn't throw (not throw) so much food away.
  3. If we borrowed (borrow) books and DVDs from libraries, we wouldn't have to (not have to) buy them.
  4. If we drank (drink) water from the tap rather than bottled water, we would save (save) a lot of money.
  5. If everyone wore (wear) an extra jumper or two in the winter, they could turn (can) down their heating and save money.
  6. If degree courses were (be) shorter, students would spend (spend) less on tuition fees and accommodation.
  7. If we turned off (turn off) the lights every time we left a room, we would not use (not use) so much electricity.