Nature has a prefect system for recycling water. Water is used again and again .It falls as rain. -1- it goes one of three places. It might seep slowly through the soil -2- it soaks through into the natural reservoirs -3-. It might disappear into the air by -4- quickly. It might -5- into streams to rivers and to the oceans.
There is a problem -6- this recycling system. It is a balance that can be easily -7- by people. Nature s recycling system can work well -8- people work with the system-not -9- it. Some ways that people -10- with nature are easy -11-. Dirty sewagewater from homes and factories must not -12- with drinking water. People would get sick from drinking dirty water.
-13- other ways that people hinder nature. Some of these ways are not so easy to understand. -14-, a marshy bog may not be good for everything, but it -15- an important purpose. The soft, wet soil of a bog -16- water to reachthe underground reservoirs. What happens to the balance of nature if the bog is filled in? Many housing development projects have been built -17- marshes once were. The -18- of the houses are likely to have problems. They are likely to -19- water, to flood in -20- seasons. Huge storm sewers are built to carry away with the water from wet areas. These huge pipes prevent wet basements in the houses of teh community.
1. [A] Therefore[B] Then [C] Consequently [D] Nevertheless