蛇是田鼠的天敌，是农田作物的卫士。上世纪末期，一些地区的人们以蛇等野生动物作为餐桌上的美食。由于过度捕杀，蛇等野生动物的数量锐减，致使农业生产因鼠害而减产。下表是-八年级生物

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• — Listen! Jane is singing in the next room.— It be her. She has gone to New York.A．can’tB．mustC．shou
• ---Where is Tom? ---He hasn’t come to school today. I think he be ill.A．has toB．shouldC．mayD．need-九年
• 要提高生态系统维持稳定性的能力，最有效的方法是[]A．减少分解者的数目B．增加食物网中的生物种类C．改变环境中的湿度D．减少消费者的数目-八年级生物
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• —Must I hand in my homework now， Mr.Smith?—No，you ________.A．can’tB．shouldn’tC．wouldn’tD．needn’t-七年级
• —Look! The man at the gate _______be our headmaster. He is always standing there every morning.—No,
• –Who is the man over there ? Is it Mr. Li? --No, it_____be him . Mr. Li is much taller.A. mustn’t B.
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• “牛喜欢吃三叶草；三叶草结子要靠土蜂传粉；田鼠吃土蜂的蜜和幼虫，捣毁土蜂的巢；猫捕食田鼠。因此养牛的农民可多养猫。”这是达尔文描述的生物之间的关系。（1）生物与生物之-七年级生物
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• 阅读有关凯巴森林的资料，分析并讨论这个生态系统稳定性被破坏的原因。在1906年以前的凯巴森林中，每当黑尾鹿的数量增加，就需要森林提供更多的食物，从而造成森林中的植被减-八年级生物
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