15.　　 Estuaries also contribute to economy through tourism and fishing.

河口还为人类提供了休闲和教育的场所。

短文改错 A man works in a factory and get his pay at 1._____ 　 the end of week. One Saturday he got his pay 2. _____　 then counted the money. Suddenly he found that 3. ________　 it was wrong：there were five pounds much than 4. _______　 he should get. He had put the money in his 5. ____　 pocket and said nothing with others. A week 6._____ 　 went by and it was pay day too. But this time 7. ______　 there were five pounds less instead of. He was 8._______ 　 so angry and he went to see the boss. The boss 9. _______　 said to him. “Didn't you notice there was a 10. ________　 mistake last week? For one mistake, I can shut my eyes, but for two mistakes, no, I can't.”

改错 1.get 改为 gets 　　　2. week 前加 the / every / each 　　　3. then 改为 and 4. much 改为 more 　　　5. 去掉 had 　　　6. with 改为 to 　　7. too 改为 again 8. 去掉 of 　　　9. and 改为 that 　　　10.√

14.　　 Scientists and students have endless opportunities to study a variety of life in the habitat.

科学家和学生有无限的机会在这块动物栖息地进行各种各样的生物研究。

13.　　 Our future depends on it.

我们的未来取决于它。

12.　　 The most important thing we can learn about water, however, is that we must protect it and use it wisely.

然而，我们了解于水的最重要的事情是：我们必须好好保护并明智地利用它。

11.　　 Most animals and plants are sensitive to large or sudden changes in temperature.

　 大多数的动物和植物对温度的大的或突然的改变非常敏感，

10.　　 Water can absorb and give off a lot of heat without big changes in temperature, thus creating a stable environment.

水可以吸收或放出大量的热量而其温度不会变化很大，因此，能创造一个稳定的环境。

9.　　　　 The circulation adds energy to the marine ecosystems and moves nutrients around.

这种循环使海洋生态系统增加了能量，从而使营养物质向四周移动。

8.　　　　 Marine animals and plants take advantage of the density of water.

海洋动物和植物利用了水的密度的特性。

7.　　　　 The nutrients in whatever falls into ocean will quickly become available to other living creatures.

通过任何渠道进入到海洋的营养物质都能很快被其他生物所利用。