一条食物链中，兔子不吃狼，但狼吃兔子，该食物链的不可逆性说明一个生态系统中（）A．氧循环是单向的B．水循环是单向的C．碳循环是单向的D．能量流动是单向的-生物

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• How much_____ these carrots?[ ]A. areB. isC. doD. does-七年级英语
• — Well, let's go to visit the amusement park this Saturday.— That _______ great. [ ]A. feels B.
• 用所给动词的适当形式填空1. Special 2 _______ (be) only 2 RMB for 10, and _____ (have) cabbage and mutton.2. Than
• — Shall we meet at the station at 8 a.m.? — In fact we _________. The train _________ until 10 a.m..
• 下列各组生物中，属于生产者的是（）A．蘑菇和青菜B．河蚌和海带C．水草和小麦D．病毒和玉米-生物
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• I’m very glad I have my own room in my house. I ______ do what I want in it.A．mustB．have toC．needD．c
• Li Lei and I ______ good friends.[ ]A. areB. am C. is D. be-七年级英语
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• Here _____some flowers.[ ]A.isB.areC.amD./-七年级英语
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