Complete each second sentence using the word given, so that it has a similar meaning to the first sentence. Write between two and five words.

1.  The Earth's weather is regulated by rainforests.

2.  Only 2 percent of 250,000 known plant species have been investigated (by scientists) for their possible medicinal value.

3.  Projects to ensure the survival of the ecosystem are constantly being developed by environmentalists.

4.  Tougher environmental laws will need to be passed by governments and elected officials.

5.  The Hawaiian monk seal was nearly driven to extinction by the oil exploration business.

6.  The environment was being protected by Greenpeace long before it became fashionable.

7.  The blue whale had been hunted by whalers almost to extinction.

8. According to some estimates, greenhouse emissions will have been reduced by countries in five years.

9.  A predator had never been faced by the dodo before its natural habitat was invaded by humans.

10. The elephant population is going to be destroyed by illegal hunters.

Acid rain is a problem in our world. It causes fish and plants to die in our waters. It causes harm to our own race as well because we eat these fish, drink this water and, eat these plants.About 20 years ago scientists first believed that acid rain was due to entirely air pollution. They were partially right. Since the beginning of the Industrial Revolution in England, pollution had been affecting all the trees, soil and rivers in Europe and North America. The use of fossil fuels, such as coal and oil, are largely to be blamed for almost half of the emissions of sulfur dioxide in the world. However, there is another cause.