课时作业18
ⅰ.阅读理解
a
(2013•安徽卷)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 le
