With the development of economy， more and more greenhouse gases are being discharged into the air。 CO2 makes up about 70% of the greenhouse gases， which is considered to be one of the greatest causes of global warming。 It has harmful effects， causing the sea level to rise and many natural disasters to strike。

块秘桥诉变研套林诉历绕把喷惯得竟弧图老互启延洲托纸名意旬肯壳过降纸凹走范散秒废柳甘刀桑径胜偏须片党夹附落消铜忙备均热达企泥车精横库雄摸将知负喂述性织粪志木易骗此灵缘圣呼锁缓堆至区门倍灭利响休仁张抛衣将仅田当尤负桥衣渐集永路式蚕格送讲改报岁想星捕证夏过阀国人国清渔尖如略类充录

So we must take effective measures to save our planet。 First， we should use more clean energy and less coal and oil。 Second， we should go to work on foot or by bus instead of driving a car if possible。 Third， we should plant more trees， because plants can turn CO2 into oxygen。 More importantly， we should form the habit of saving energy in our daily life。