图为胸腔和肺的示意图，当肋间肌和膈肌收缩时，图中三部位压力由小到大的顺序是（）

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A：c＞a＞d

B：a＞b＞c

C：a＞c＞d

D：b＞c＞a

上一题下一题 0.0难度选择题更新时间:2017-05-31 03:46:17

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B

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阅读理解
(Mr. Zhang is showing Wei Fang and Li Lei a modern factory.)
Mr. Zhang: You can’t see many workers here, but you can see a lot of robots. Look, that robot has two big hands.
Wei Fang: How strong it looks!
Mr. Zhang: Yes. It does much work for us.
Li Lei: There are so many big boxes here. What are the robots doing?
Mr. Zhang: They are making fridges.
Wei Fang: How fast they are working!
Li Lei: How much time do they need to make a fridge, Mr. Zhang?
Mr. Zhang: About five minutes.
Wei Fang and Li Lei: Only five minutes! What a modern factory it is!

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下列有关生物知识的叙述正确的有
①碳元素是构成生物体有机物的基本元

素，可形成链式或环式结构，在一个二十三肽的化合物中最多含有肽键23个。
②细菌和植物细胞都有细胞壁，但其主要成分不同。
③葡萄糖存在于叶绿体中而不存在于线粒体中。
④人和动物细胞在无氧条件下也能分解有机物，释放能量，并产生C0₂
⑤生长激素、胰岛素、甲状腺激素都含有肽键，均可用双缩脲试剂来鉴定。

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