题干

幼小植物体内自由水与结合水的比值不断增大时,植物体内新陈代谢活跃,生长迅速;自由水与结合水的比值不断减小时,植物体内的新陈代谢减弱,生长缓慢.下面解释正确的组合是(    )

①结合水是构成植物细胞结构的一部分;

②结合水参与某些代谢反应;

③自由水是各种代谢活动的介质;

④自由水参与某些代谢反应

A:①②

B:②③

C:③④

D:①④

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答案(点此获取答案解析)

C

同类题1

阅读理解

    Travelling around the world with children is difficult enough, while attempting it without using motorized transport is even more of challenge.Even so, Dario Schworer a 42-year-old climatologist and mountain guide, and his 33-year-old wife Sabine are on a journey to do just that.

    The Swiss couple want to travel across the world's oceans and climb the highest mountain on every continent to promote Earth-friendly ways of life.

    "We are collecting good examples of dealing with climate change and living in harmony with nature and we want to spread such ideas." Schworer said."We want to help people affected by global warming and to inspire children for the future."

    Recently after having spent three months teaching children in the Everest region, the couple want to show it is possible to travel through the world's climate zones using just human-power and forces of nature.

    In the 47 countries they have visited they have collected 22 tons of trash, taught people in Ecuador how the sun's rays can be used to clean water and inspired a person in Chile to build a house on water with recycled plastic bottles as a foundation.They have also collected trash in the mountains of Nepal with school children.

    So far they have communicated with 45,000 children from South America, Australia and Asia, giving presentations about the importance of recycling and using alternative energy like solar and wind power.

    When they began their adventure in 2003 they had no children of their own.But since then two has become five: daughter Sabine is now five years old, Andri was born in Chile and baby Neo was born in Australia.

    Initially the couple thought they would complete their travels in four years, but now, they believe it could take seven more.

    "Since our belief is the need to respect nature, we travel only when conditions are good," Schworer said.

同类题4

阅读散文《永不放弃》,完成小题。
                                                                                                永不放弃
      ①那天一大早,我15岁的儿子鲍伯又和我争吵了起来。他要穿那件剪掉了袖子的褪了色的旧运动衫去上学,而我则坚持让他穿圣诞节他奶奶送给他的那件印着蓝色花押字的漂亮衬衫。我用手指着那些字母:“并不是每个人都能穿上印着自己名字的大写首字母的衬衫的。”我跟他讲道理。
  ②他的眼睛骨碌碌地转动着,但并不看我,而是看向了厨房的天花板。“没有人会穿印着自己名字的大写首字母的衬衫的,妈妈。没有人!”
      ③没过一会儿,我们就开始冲对方大呼小叫起来。他开始出言不逊,我的话也很不中听。最后,他很不情愿地将奶奶送的衬衫套在身上。当他拿起书本的时候,我伸手去拥抱他,却被他硬生生地抽身走开了。
  ④事实上,自从鲍伯进入青春期以后,我就真的不知道该如何管教他了。最近,我们之间起了太多的冲突和争吵,他对我说的每一句话都持怀疑的态度,我都准备甩开手不管他了。
  ⑤我叹了口气,出门向家门口的邮箱走去。我的邮箱曾被汽车撞坏过,箱门关不严。我把手伸进去,碰到了一叠信封,然后是一些特别的东西,像扫帚须。我朝邮箱里窥视,那天的信放在一小堆杂草和松枝的上面。谁干的恶作剧?我想。便随手将杂草拨拉出来。
⑥第二天,当我去邮箱里取信时,邮箱里又有了一小撮松枝、一些细树针、两朵干枯了的蒲公英。此后每天,我都能在邮箱里找到一些杂草,每天,我都将它们清除出去。
⑦星期六,鲍伯走进书房,我正在看报。“妈妈,我可以去看电影吗?”他问。
  ⑧“不行,这个电影你不能看,因为你没到18岁!”我神情坚定地回答。
  ⑨“难道我们连谈谈它也不行吗?”他恳求道。
  ⑩“没什么好谈的,”我说,“我们的谈话只会以大呼小叫告终。”
  ⑪“妈妈,你不可理喻,”他叫道,“你连试都不愿意试一试!”
  ⑫又到了取邮件的时间,我像往常一样走出家门,邮箱里又有一些令人恼火的碎草叶,我伸手进去将它们往外拨拉,突然在那些细树枝和杂草的中间碰到了一些又小又圆的东西,我一惊,手猛地缩了回来。一看,原来是青色的鸟蛋。
  ⑬就在那时,我听到附近一棵树上传来一阵叽叽喳喳的鸟叫声。我的目光在树枝和树叶间搜索了一阵,发现鸟妈妈正衔着一根松枝,松枝在它的喙边晃悠着。我被鸟妈妈的坚韧毅力所感动,重新将那粗糙的鸟巢推回邮箱里去。原来,它每天在我们的破邮箱里筑巢,当它飞回来发现自己所有的努力都被一扫而空时,它又重新开始筑巢。
  ⑭“你连试都不愿意试一试!”鲍伯的话又在我的耳边响起。
  ⑮他正心不在焉地坐在自己的书桌前转动着地球仪。“嗨!”我说。他抬起头看了看我,眼睛瞪视着,在那一瞬间,我不仅看到了这个尚处于少年时期的既脆弱又敏感的小男孩,也看到了即将长成年轻人的未来的他。“想谈谈吗?”我问,“我保证会认真听你说。”
  ⑯我坐在那儿,听他将自己的愤怒、怨恨全部倒出来。那天,我们之间的痛苦和隔膜似乎全被消化掉了,我们有了一个全新的开始。
  ⑰后来,邮箱里出现了三只幼鸟,鸟妈妈每天都栖息在邮箱顶上唱歌。听着那些歌声,我暗暗下定决心,不管儿子多么不听话,多么难以管教,我永远不会放弃对他的教育,引导他长大成才。