如图所示为草原生态系统的食物网示意图，能量从蛇传递到鹰的效率约为（）A．10%～20%B．50%～60%C．80%～90%D．100%-生物

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• 句型转换。1. My mother can play table tennis.(改为否定句) My mother ______ ______ table tennis. 2. Lingling�
• Who is it be. it _____ be susan.it _____be susan.he is in beijing now.[ ]A.may . can't B.can.ca
• Sixteen-year-olds to watch this kind of movie because it's too scary.[ ]A. should allow B. shou
• 如图表示某生态系统中食物网简图．图中甲--庚代表各种不同生物．请据图分析回答：（1）此生态系统中作为生产者的是______，消费者是______．（2）若此生态系统受重金属污染，那么在体-生物
• 根据句意，从方框内选择合适的情态动词完成句子。must, may, can, could, might, can't1. The brown walletbe Tom's or B
• 有关“生产者是生态系统的主要成分”的理解，正确的是（）①生产者能将无机物合成有机物，属于自养型生物②生产者的细胞呼吸将有机物分解成无机物，实现了物质的循环③绿色植物的蒸-生物
• She ________ hum pieces of music at the age of four. She is a talented singer. [ ]A. can B. could C.
• — ______ I have a ticket, please? — Sorry, sir. All the tickets were sold out ten minutes ago. [ ]A.
• —Must I park my car behind the building?—No, you _ . You _ park it here.[ ]A. mustn't; may B. m
• 用must, mustn't, can, can't填空。1. Don't open your present now! In China you _____ wait
• The backpackbe Linda's. It be Grace's. I saw it at herhome before.[ ]A. mustn't, must
• 在自然界中，树木不断掉落树叶，动物不断地死亡，却不会出现树叶和动物尸体堆积如山的状况，这主要是因为（）A．被雨水冲走B．大雪掩埋C．树叶被风吹跑，动物尸体被秃鹫取食D．分解-生物
• 关于生态系统的能量流动，下列叙述中不正确的是（）A．稳定的生态系统必须不断地从外界获取能量B．生态系统中的能量最终来自于太阳能C．生态系统的能量流动可以循环进行，提高能量-生物
• 某一湖泊生态系统的食物链为藻类→虾→小鱼→大鱼，此食物链中的四类生物按顺序以甲、乙、丙、丁为代号建立能量金字塔（如右图）．今有10只人工饲养的鳄鱼逃逸栖居进入该湖泊，则该-生物
• My pen pal told me that he come to watch the Olympic Games in August 2008. [ ]A．will B．would C．can D
• —_____ you read books? —Yes, I _____.[ ]A. Can, do B. Do, can C. Can, can D. Can, read-七年级英语
• —Is the man over there Mr White?—No, it_____ be him. I saw him in the office a minute ago.[ ]A. may
• It's cold outside . We _____ stay in the classroom[ ]A.mustB.can C.havetoC.might-八年级英语
• I thought youlike something to read, so I have brought you some books.[ ]A. mayB. mightC. canD. coul
• 生态系统中能量流动的特点是（）A．循环往复，逐级递增B．单向流动，逐级递增C．循环往复，前后不变D．单向流动，逐级递减-生物
• 在一个稳定的池塘生态系统中，一种突发的污染使所有的植物死亡，在科研测量的变化中，首先降低浓度的是（）A．二氧化碳B．无机盐C．氧气D．一氧化碳-生物
• 根据如图生态系统中的生物，分析回答下列问题：（1）请在图上用箭头画出所有的食物链．（2）这个生态系统共有______条食物链，它们相互交错形成______，写出最长的一条食物链：____-生物
• 用can或can't加下面一个动词填空。 speak, see, hear, play, color, ask, drive, fly, spell, go1.I'm sorry
• —Could you please tell me the way to the station?—Sorry, I’m a stranger too. You ______ ask the poli
• —_____ he play table tennis?—No, he _____. [ ]A. Is; isn't B. Can; can't C. Can; isn'
• 在生态系统中，下列哪项是消费者（）A．蘑菇B．野兔C．阳光D．牧草-生物
• — I keep the book a little longer?—Yes, you can.[ ]A. MustB. NeedC. CanD. Should-九年级英语
• —_____I get home before 7 ? —No, you needn’t.[ ]A. Must B. Should C. Can D. Will-八年级英语
• I often see lights in that empty house. Do you think I ______ report it to the police? [ ]A. should
• 句型转换。1. It's necessary to study hard in the school.(同义句)______ ______study hard in the school.
• 下列叙述正确的是（）A．在一个生态系统中，生产者、消费者、分解者是紧密联系、缺一不可B．维持生态平衡，就是维持生态系统内部各种生物的数量稳定不变C．人类所需的资源中，土地-生物
• _____ you ride _____ horse? [ ]A. Are; the B. Can; a C. Are; a D. Can; the-七年级英语
• 若人吃的牛肉来自以玉米为饲料的牛，人和牛分别扮演的角色是（）A．生产者消费者B．消费者生产者C．消费者分解者D．消费者消费者-生物
• —Bill, is the pink umbrella Anna’s?—No, itbe hers. Hers is purple. [ ]A. canB. may not C. wouldD. ca
• 如图示草原生态系统，请分析回答：（1）此生态系统中的生产者是______，分解者是______、______．（2）生产者与消费者之间的关系主要是______的关系它们之间相互交叉形成了______，
• 从“狼吃羊，羊吃草”可以看出，狼体内的有机物最终来源于（）A．草B．水C．羊D．阳光-生物
• You_____ be so hurry as the time is not so late.[ ]A. mustn’t B. mustC. can notD. will not-八年级英语
• 根据句意，从方框内选择合适的情态动词完成句子。must, may, can, could, might, can’t1. The brown wallet_____be Tom’s or Bill’s
• — This capTina's. I know she has a red cap. — No, it be Tina's. I am wearing her cap now.
• —How about singing songs with me?—I’m sorry I can’t. Ihelp my father with his work. [ ]A. have toB.
• 把下列生物与它在生态系统中所占的位置用线连接-生物
• - your brother play basketball, John? -No, he .[ ]A. Is; isn'tB. Can; canC. Can; can'tD. A
• "Must I come here before eight o'clock?" "No, you ______." [ ]A. can'
• 请按各小题的要求转换句型，保持句子原意，每个空格只准填一个单词。 1．We don't usually have to get there too early. (改为同义的) We get
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• 要使某一生态系统长期存在，除了非生物部分外，必须具有（）A．消费者和生产者B．生产者和消费者C．生产者和分解者D．生产者和人-生物
• Jack _______ swim when he was five years old. [ ]A. canB. could C. may D. must-八年级英语
• 下列说法错误的是（）A．我们饮用牛奶所获得的能量最终来自于太阳B．如果在人的皮肤表皮细胞内成功植入叶绿体，则我们人也能向植物一样进行光合作用C．植物的蒸腾作用会受到各种物-生物
• 下列各项生物中，属于生产者的是（）A．水草和小麦B．鱼虾和海带C．蘑菇和青菜D．食草鱼类和玉米-生物
• —Must I finish the job this afternoon?—Yes, you _____, but you ______ finish it now.[ ]A. must; must