(沙尘暴)
1．沙尘暴已成一大祸患；
2．沙尘暴形成的原因；
3．结论。
[写作导航]首先描述沙尘暴的严重程度及其危害，如不少城市和乡村每年都受沙尘暴的袭击，造财产损失甚至人员伤亡等；第二段分析造成这一危害的原因，如空气污染造成温室效应以及水土流失、乱砍滥伐等；第三段结尾，警告人们吸取大自然给人类的教训，发展生产的同时不要忘记环境保护。
[范文]


Duststorms are becoming a great concern for both the public and the government in recent years. Every spring overwhelming sands and dust sweep the northern part of China, blocking out the sky, enshrouding cities and villages, bring much inconvenience and problems to people＇s lives and work. In some regions, sandstorms have caused great loss in both people＇s lives and properties.


Duststorms are largely created by man himself. On the one hand, too much air pollution causes a greenhouse effect, which, in turn, leads to global wanning in climate. This results in wet places on the earth even wetter and dry places even drier. On the other hand, over grazing, poor fanning, tree cutting, strip mining all leave theland unprotected. When the wind blows, it blows away topsoil and loose soil.


Duststorms are another punishment nature gives to mankind. We must be alert to this ecological alarm. We should not only take effective measures to stop duststorms but also draw some lessons from it. We should not "develop" the local economy at the cost of the natural environment.