阅读理解。

　　The Great Lakes between the US and Canada are the largest bodies of fresh

water in the world. For a long time, people lived happily beside the Lakes until

the countries began to build factories along the shores. Pollution was killing the

Lakes, pretty soon, the Lakes' ecosystem (生态系统)was not right any more.

Scientists knew something had to be done.So did the government(政府). They

learnt it was important to keep the ecosystem of the Lakes healthy and strong. If

the Lakes dried up, the whole world would feel it.

Many areas would become deserts and many animals would lose their homes and

maybe die out. As a result, they set up a lab called the Great Lakes

Environmental Research Laboratory to solve(解决)the problem.

任务1：根据英文释义及首字母提示，拼写单词。

1. d____to stop living

2. s____the land along the edge of a large area of water,such as an ocean or lake.

任务2：同义句转换，每空一词。

Scientists knew something had to be done. So did the government.

3.____scientists 4.____the government knew something had to be done.