1. However, the natural processes for filtering water can clean only a certain amount of water by removing the pollution.
    但这些过滤水的自然作用通过去污仅能净化一定量的水。

2. Human activities can cause or accelerate permanent changes in natural systems.
    而人类活动能够引起或加速自然体系中的永久性变化。

3. Animals in a zoo are not living in their natural surroundings.
    动物园里的动物不是生活在自然环境之中。

4. And upsetting the natural water cycle (循环) on Earth makes significant problems for its inhabitants.
    扰乱地球上水的自然循环会对它的居民造成严重问题。

5. According to my mother, my natural parents were Samoan and only teenagers when I was born, so they gave me up for adoption.
    母亲告诉我，我的生身父母是萨摩亚人，我出生时他们才十几岁，所以他们把我送给别人抚养。

6. All natural systems tend toward balance among opposing factors or forces.
    所有自然体系都趋向于在各种对立因素或力量中保持平衡。

7. Actually, recycling is one of the least important things we can do, if our real objective is to preserve natural resources.
    实际上，如果我们的真正目的是保护自然资源，那么回收利用则是我们能做的工作中最不重要的事情之一。

8. A new arrival on the anti-wrinkle front claims to be a more natural way to avoid those terrible lines.
    抗皱行列的一个新产品声称可以用一种更自然的方法来避免讨厌的皱纹。

9. Yes, the earth's resources are not infinite; natural areas are being destroyed; the number of plant and animal species is declining; consumption of resources is expanding.
    是的，地球的资源不是无限的，自然界在遭受破坏，动植物的物种数目在减少，而资源的消耗却在增加。

10. Some natural sorrow, loss, or pain,
    是那寻常的忧愁，失落，或者痛苦，