Вставьте a/an в пропуски.1…

Вставьте a/an в пропуски.1… . garbage is not only, but dangerous because it causes … air pollution.2. In Canada people don't realise that they throw out 10,000 tons of … waste.3. Cars are … important part of … life for most people. But cars also cause … pollution and release fumes.4. Over 14 billion pounds of … waste per year is thrown out to sea and it kills millions of sea animals.5. If we want to breathe … healthy air we have to think about what we do.6. Because of our lack of … knowledge there is now … huge hole over … Antarctic.7… . water is … vital element of … life.