篇篇学之1：Introduction to Dam

A dam is a structure built across a stream, river or estuary to retain water;
大坝是横跨在溪流，江河或者河口上的建筑物；
Some dams are tall or thin,while others are short and thick.
有些坝高而薄，而有些坝低而厚
Dams are made from a variety of materials such as rock, stell and wood.
大坝是有各种各样的材料浇筑而成的，如石头，钢材和木材
Dams affect society in many positive ways.
大坝在许多方面都有益于社会
Dams gather drinking water for people.
大坝可以聚集人们的饮用水
Dams help farmers bring water to their farms.
大坝帮助农民将水灌溉到他们的农田里
Dams help create power and electricity from water.
大坝对于水力发电也有好处
Dams keep areas from flooding.
大坝可以使某些区域免受涝灾
Dams create lakes for peaple to swim in and sail on.
大坝可以形成湖供人们游泳和游船。
Dams also aid in navigation by making waters deep and calmer.
大坝可以形成深而静的水域，有利于航运。


不知这样翻译怎么样？

钢材是steel呵呵。内容真的很不错！