In June of 1973, nine whales beached on th

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In June of 1973, nine whales beached on the Florida coast. Beaching means swimming out of the ocean onto the beach, and usually dying there. No one knows why they do it, but a number of whales beach themselves every year. Some people think beaching is an accident.
Perhaps the whales get confused. Scientists who studied the beaching of three dozen whales in Australia think the whales may have been confused by loud noises, Whales can tell where they are by sounds. They send out sounds and listen as they travel past or bounce off objects. Two days before these thirty-six whales beached, loud guns had been fired for two hours. The loud sounds may have confused the whales. Their confusion might have caused them to wander into low water.
Whatever the reason whales beach, it is a sad event. People try to save them, but very few beached whales live. One whale that was rescued from beaching in Florida lived for forty-five days. That is the longest a beached whale has ever survived. And it lived that long only because it got attention from doctors.
All over the world, scientists rush to whale beachings as soon as they hear about them. They hope to learn why whales beach, and how to save them.

Whale beachings are sad events because ______.

A.people know the whales are going to die

B.the whales have to be carted away and buried

C.the whales cannot be used as food

D.no one can use the beach on those days

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A.血浆肾素水平升高,醛固酮水平降低

B.血浆肾素水平升高,醛固酮水平也升高

C.血浆肾素水平降低,醛固酮水平也降低

D.血浆肾素水平降低,醛固酮水平升高

E.血浆肾素和醛固酮水平均无变化

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标准状况下,2.24L某气态烷烃完全燃烧生成H2O的质量是9g,该烃的分子式为()

A.CH4

B.C2H6

C.C3H8

D.C4H10

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大站电源屏,当外电网输入的交流电压在V的范围内变化时,交流输出电压应稳定在()的范围内。

A、380V±7.6V/220V±4.4V

B、380V±11.4/220V±3.3V

C、380V±15.2V/220V±8.8V

D、380V±19V/220V±11V

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简述在Excel中进行分类汇总的操作步骤。

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组织兴奋性降低,组织的 ( )

A.静息电位值减小

B.动作电位减小

C.刺激阈减小

D.阈值增加

E.反应性增加

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