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当今全球环境问题变得越来越严重。请你根据漫画内容，以李华的名义给“China Daily”写一封信，描述这种状况，并提出保护环境的建议。注意：1）．不要拘泥于要点，可以适当发挥，词数100左右。2）．参考词汇：人口膨胀：population expansion；过度开发：overdevelopmentDear Editor, ……Yours sincerely,Li Hua 答案：Dear editor, Environmental problems are becoming more and more serious all over the world. With the development of society, private cars make great noises and give off poisonous gas, which does great harm to the environment. As we all know, waste water from factories is poured continuously into rivers without being treated. Worse still, because of population expansion and overdevelopment, the prob12．如图所示，在两等量异种点电荷的电场中，MN为两电荷连线的中垂线，a、b、c三点所在直线平行于两电荷的连线，且a与c关于MN对称，b点位于MN上，d点位于两电荷的连线上．以下判断正确的是（　　）A．b点场强小于d点场强B．b点场强等于d点场强C．a、b两点间的电势差小于b、c两点间的电势差D．试探电荷+q在a点的电势能小于在c点的电势能