在一个由草、野兔、狼组成的相对封闭的生态系统中，如果将狼杀绝，在一段时期内野兔的数量变化可用下列哪一曲线图来表示[]A．B．C．D．-七年级生物

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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
• 下列关于生态平衡的叙述中，错误的是[]A．生态平衡是一种动态和相对的平衡B．生态平衡依赖于生态系统的自我调节能力C．生态系统的自我调节能力是无限的，自然因素不会破坏生态平-八年级生物
• —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.
• You ___________ follow the traffic rules. Otherwise, it is dangerous for you.A．must B．canC．mayD．shou
• — Must I stay here with you?— No, you . You may go home, but you go to the net bar (网吧).A．mustn’t；do
• “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
• — Can we leave the classroom now?— No, you ______. You ______ to leave until the bell rings.A．mustn
• —May I do the rest of the work tomorrow?—Yes, of course. You finish it today.A．needn’tB．mustn’tC．nee
• — What do you want to eat for lunch? I will prepare it earlier today. — You_____, mum. Let’s go out
• 在一定的时间内，一个自然生态系统内的生物种类和数量一般是相对稳定的，它们之间及其与环境之间的能量流动和物质循环也保持相对稳定，这种稳定称为__________。-八年级生物
• 自然界中的生态系统都能在较长时间内保持相对稳定，其主要原因是[]A．具有复杂的食物链结构B．消费者种类和数量多C．生产者的种类和数量多D．生态系统具有一定的自我调节能力-八年级生物
• 下图是某生态系统食物网的一部分图解。请据图回答：（1）该示意图表示的只是某一食物网，若要表示一个生态系统，还有_________和________________两个部分未画出。（2）此食物网中-八年
• —Whose workbook is this, Tony?—Look! Ann's name is on it! It ______ be hers.A．can'tB．mustC
• ---Look at the glasses on the desk. Are they David’s?---They belong to him. I saw him go out with gl
• 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
• ---Lucy doesn’t mind lending you her dictionary.---I think she doesn’t, but I ________do so. I’ve al
• ---Look at that girl! Is that Susan?---No , it _______ be her. She has gone back to her hometown.A．m
• You ___ cross the road when the traffic lights are red. It’s dangerous. A. needn’tB. may not C. must
• —Let’s go to Zhongshan Park by taxi.—It’s not far. We _________ take a taxi.A. needn’t B. can’t C. m
• Teenagers _______ allowed to drive in the street．A．should not beB．should be notC．not should beD．shou
• —Why is online shopping getting more popular? —I think it _________ save a lot of time.A．shouldB．had
• It is usually warm in Nanjing in spring. But sometimes it be very cold.A．mustB．wouldC．canD．should-八年
• It’s said that there are plenty of hotels in that town. There ____________ be any difficulty for you
• —Look at the boy running on the ground. Is it Davis?—It ______ be him. I saw him go to the teacher’s
• 生态平衡是一种动态和相对的平衡。[]-八年级生物
• ---Could I go boating this weekend, Dad?---Yes, you ________. But you ________ come back before lunc
• —____ I swim here?—I’m sorry. Children ____ swim alone here..A．Must, can’tB．May, mustC．Can, mustn’tD
• 生态平衡意味着生态系统中各种生物的数量是恒定不变的。[]-八年级生物
• With the help of the smart phones, you ____ video chat with your friends on the phone.A．canB．mustC．n
• —Honey, stay at home before I return.—I, mum.A. must B. can C. will-七年级英语
• —May I use your computer, Mr WU?—______．A．Yes, you may notB．No, you mayC．Yes I mayD．No, you may not-
• —Whose shirt is this?—It ______ be Li Lei’s. It is too big for him.A．couldB．mustC．mightD．can’t-八年级英语
• If you know nothing about the famous program called Where are we going, dad?, you ______be living in
• —Can you play the violin? —_____. But I can sing.A．Yes, I doB．No, I don’tC．Yes, I canD．No, I can’t.
• Look, Grace just takes after the man. I think he be her father.A. must B. can C. can’t -八年级英语
• — The Queshi greenway has become a popular place for Shantou people on the weekends. — That’s right.
• —May I take photos in the museum? —No, you . You obey the rules here.A．may not; canB．mustn’t; mayC．c
• ----Must I leave now?----No, you _________. There is still some time left.A. mustn’tB. needn’t toC.
• —Shall I help you prepare for the dinner?—No, you ________. Everything has been ready.A. can’t B. m
• ---Someone is knocking at the door. Is it your brother?---No, it be him. He’s gone to Hunan.A．mustn’
• —Listen! Is Mary singing in the next room?—No. It _______ be Mary．She has gone to Shanghai for an im
• ---Must I finish my homework now ? ---No, you ________A．shouldn’tB．mustn’tC．needn’tD．can’t-八年级英语
• —You praise your son. He works harder than before. —Thanks, I will.A．should B．canC．mayD．must-九年级英语
• 请根据中英文提示或句意，写出句中所缺单词，使句子通顺。(5分）小题1:My parents love sports, e_________ walking and jogging.小题2:There
• 生态平衡是一种[]A．绝对平衡B．动、植物的数量相对平衡C．动态平衡D．永久的平衡-八年级生物
• — I’m a little tired. Let’s go to the zoo by taxi.—We ________take a taxi. It’s not far from here.A．