1.The researchers saw the site where icebergs broke off.
2.That't why an effective but low-cost clean-up method is required.
3.The time will come when tropical rain forests are totally destroyed .
4.The Environmental Ministry officials investigated the area where air pollution was thick.
5.I see no reason why a lot of farmers use excessive pesticides and chemical fertilizers.
6.This is how sulfur dioxide contributes to acid rain in Schwarzwald.
7.The National Trust was founded in 1895 when people started to be concerned about the pollution problem.
8.Henry studied the climate of Australia, where famous coral reefs were heavily damaged.