2．which　先行词为物，定语从句用介词＋which 引导。

　　3．length　in length 长。

　　4．up　up to 多达。

　　5．addition　in addition to 除......之外(还)。

　　6．as　as 为介词，意为"作为"。

　　7．so　so that 目的是。

　　8．the　江、河、湖、海前用定冠词 the。

　　9．protection　名词作宾语。

　　10．on　from then on 从那时起。

　　Ⅰ.阅读理解

　　Using too much water or throwing rubbish into our rivers are clear ways that humans can put our water supply in danger, but we also affect our water supply in less obvious ways.You may wonder how paving(铺砌) a road can lead to less useable fresh water. A major part of the water we use every day is groundwater. Groundwater does not come from lakes or rivers. It comes from underground. The more roads and parking lots we pave, the less water can flow into the ground to become groundwater.

　　Human activity is not responsible for all water shortages(短缺). Drier climates are of course more likely to have droughts (干旱) than areas with more rainfall, but in any case, good management can help to make sure there is enough water to meet our basic needs.

Thinking about the way we use water every day can make a big difference，too. In the United States, a family of four can use 1.5 tons of water a day! This shows how much we depend on water to live, but