下图为生态系统碳循环示意图，请据图回答下列问题。（1）由图可知，碳在生态系统中主要以_________的形式进行循环。（2）大气中的二氧化碳首先依赖于图中②所代表的_________进入-八年级生物

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• —Jack.All the young trees____at once. —OK.I'll do it at once.[ ]A. must be watered B. must wate
• —I like the party so much, but I_ go home.It's too late.—What a pity! [ ]A. have to B. mustn�
• 能量流动和物质循环是生态系统的两个密切相关、不可分割的过程。[]-八年级生物
• I __________ dance but I___________ dance well.[ ]A. can; canB. can; can'tC. can't; canD.
• 下图是自然界碳循环的简图，图中甲、乙、丙各代表[]A．生产者、分解者、消费者B．消费者、分解者、生产者C．分解者、生产者、消费者D．生产者、消费者、分解者-八年级生物
• If I went to the moon,I _____ bring something unusual back to school.[ ]A.willB. canC. wouldD. shall
• 在“草→昆虫→食虫鸟→鹰”这条食物链中，全部昆虫消耗的能量比全部狼所消耗的能量[]A．多B．少C．相等D．大约相等-八年级生物
• —Could I use your pen? —Of course, you _______.[ ]A. must B. may C. can -九年级英语
• 在生态系统的碳循环中，二氧化碳进入生物体内是通过[]A．呼吸作用B．光合作用C．蒸腾作用D．扩散作用-八年级生物
• —Let's go to the movies tonight.—Sorry.I__ . I have to help my mother wash clothes.[ ]A. mustn&
• —Where's my watch? I can't find it anywhere.—It _ _ in your bag or under these books.[ ]A.
• 古书《说苑．正谏》中有这样一段记载：“园中有树，其上有蝉，蝉高居悲呜，饮露，不知螳螂在其后也；螳螂委身曲附欲取蝉，而不知黄雀在其傍也；……”这是比喻社会现象的寓言，但却反-八年级生物
• —He is tired now.He_____ stay at home and have a rest.—Thanks, doctor.[ ]A. has toB. maysC. needD. c
• —Could I borrow your dictionary?—Of course I _____.[ ]A. canB. mustC. shouldD. have to-八年级英语
• Henny _________be at home now because he phoned me from the school just now .[ ]A.mustn't B.isn
• 在生态系统中，能量流动的起点是[]A．从生产者固定太阳能开始B．阳光照射到绿色动植物体上时C．生产者被动物所食时D．分解者分解动植物遗体时-八年级生物
• Return home quickly. Your parents _____ be worried about you now.[ ]A. canB. may C. must D. could-九年
• 下图是有关生态系统中碳循环的示意图，请分析回答下列问题。（1）写出①②③④的生理过程及⑤产生C02的方式：①_________、②_________、③_________、④_________、⑤__
• 小华同学说：“爷爷讲在他小时候，村边的小河里有许多鱼、虾，稻田中有不少黄鳝和泥鳅。现在河里和稻田中几乎没有鱼、虾了。”这是什么原因呢？（1）请对上述情况做出假设：_______-八年级生物
• —Is this pair of shoes Jim's? —It _his.They're too big for him.[ ]A. might be B. can'
• —I still have a toothache. —Oh, sorry, the medicine didn't work, so you ________try another kin
• 研究生态系统的能量流动，可帮助人们合理地调整生态系统中能量流动的关系，使能量_________地流向对人类最有益的部分。-八年级生物
• I_____play the guitar.It's too difficult. [ ]A. canB. can't C. doesn't-七年级英语
• —You see, a man is cutting a tree on the moon. —It _________ be true. The teacher says there is no a
• 根据句意从方框中选用合适的词组，并用其适当形式填空 fix up take after hand out clean up call up 1.The teacher __________ all t
• That man _______ our head teacher. Our head teacher has gone to town.[ ]A. can't beB. mustn
• 改成同义句。1. Kate can't work out the math problem, I think. I ______think Kate ______work out the m
• 下图是珠江三角洲的农民充分利用自然条件，建立的该地特有的蔗基鱼塘和桑基鱼塘示意图。请据图回答：（1）这种人工生态系统最基本的生物因素是___________。要使它长期稳定发展-八年级生物
• This building is too old and dangerous.It should ___dowm[ ]A. to pullB. pullC. is pulled D. be pulle
• —I was told to be here before 6:00 p.m.— Oh, you . I felt sorry for you that we've changed the
• 生态农业的最大优点是[]A．物质循环不再生B．能量的多级化利用C．生物相互依存D．不用人类参与-八年级生物
• You ______ jump onto a bus while it is still moving. It is too dangerous. [ ]A. can B. must C. can&#
• —Must we wear our school uniform this afternoon?—No, you _____. All of us will go on an outing.[ ] A
• 句型转换1. I like playing football. (否定句)I ______________ playing football.2. I wanted soup for supper.
• You ________ your homework now.You can do it tomorrow.[ ]A.needn't to doB. don't need doC.
• My mother is ill. I __________ stay at home to take care of her.[ ]A. canB. mayC. shouldD. maybe-八年级
• 一般地说，在输入到一个营养级的能量中，只有的能量能流入下一个营养级。-八年级生物
• 在生态系统内，与碳循环始终结合在一起进行的是[]A．氮循环B．水循环C．能量流动D．能量循环-八年级生物
• —Would you like to see Beijing Opera with me tonight?—I'd like to, but I'm afraid I ______
• The little boy _____ write, but the girl can. [ ]A. may not B. must not C. can't D. needn'
• —Dad, must I practise the piano today?—No, you _. You may do it tomorrow.[ ]A. needn’tB. mustn’tC. s
• 从物质循环的观点看，生物体内碳元素的最终来源是[]A．食物所含有机物中的碳B．非生物界中的碳酸盐C．大气中的二氧化碳D．生态系统中的生产者-八年级生物
• Must I take the medicine every day?-No, you __________.[ ]A. mustB. mustn'tC. needn'tD. ca
• 由于生物自身的消耗，以及植物的残枝落叶和动物的骨骼、皮毛等难以被_____利用，造成了能量在沿食物链流动过程中是逐级的。-八年级生物
• There is no bus at this time every night. You ____ walk home.[ ]A. mustB. have toC. canD. need-八年级英语
• You _______ go to bed early, or you can't get up on time.[ ]A. canB. shouldC. mayD. must-八年级英语
• 生态系统中的能量流动伴随着__________。-八年级生物
• He ______more fruit and vegetables instead of meat.[ ]A. need to eat B. needs to eatC. need eating D
• -Must we hand in the money for the tickets now?-No, you __________.[ ]A. mustn'tB. can'tC.
• 我国北方地区，二氧化碳含量相对较高的季节是[]A．春季B．夏季C．秋季D．冬季-八年级生物