麦田中农民伯伯要拔掉杂草，用生态学观点看这是为了（）A．保持生态平衡B．保持生物种类的单一性C．调整能量在生态系统中流动的方向D．使物质能够尽快地循环流动-生物

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• —I'm sorry to have kept you waiting. —Oh, not at all. I ____ here only for a few minutes. [ ]A.
• 单项填空。Donuts ______ my favourite food. [ ]A. is B. areC. doD. does -七年级英语
• －Would you like something to drink?－No, thanks. I __________ a glass of water just now. A．drinkB．wil
• 如图是一个食物网，请据图回答问题：（1）生产者是______．（2）图中共有______条食物链，为了提高绿色作物的产量，我们应该人人保护______和______，禁止捕捉它们．（3）在生态系统中-
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• 在改写后的句子中填入所缺单词，使其与原句意思相符。1. Hiscousincouldswimwhenshewasfouryearsold.Hiscousin_____________________s
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• 生态系统中的物质和能量就是沿着食物链和食物网流动的．______．-生物
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• --- Is there a pay phone _______ the neighborhood?--- Yes, it’s____ Center Street____ the right.A．in
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• _____ people in the world are sending are receiving e-mails every day.A．Million ofB．Many millions of
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• What _____ you supposed_____when you are in Korea? [ ]A. do; to do B. are; to do C. are; doing D. ha