如图5-6所示,正方形截面对x轴的惯性矩为()。 A.A B.B C.C D.D

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问题:

如图5-6所示,正方形截面对x轴的惯性矩为()。

A.A

B.B

C.C

D.D

考点:注册环保师环保公共基础知识注册环保师公共基础知识
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关于检验效能,下列说法错误的是()

A.两总体均数确有差别时,按α水准发现这种差别的能力

B.两总体均数确有差别时,按1-β水准发现这种差别的能力

C.与α有关

D.与样本例数有关

E.与两总体均数间的位置有关

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阴离子交换树脂易在碱性介质中进行交换。

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人类的情商(EQ)目前尚无法精确测定。

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Questions 81-90 are based on the following passage.


It sounds like a science fiction, but researchers say it’s a scientific fact: Microscopic organisms dubbed "killer algae" are paralyzing fish with unknown toxins and then eating away at their flesh. They might be making people sick, too.
The name given to this single-cell organism, or dinoflagellate, is Pfiesteria piscimorte- literally, "fish killer. " It was discovered at North Carolina State University in 1988, but at the same time, few scientists believed in its existence, much less in its highly unusual predatory nature. But ongoing research has led to international acknowledgment of the phenomenon and, recently, research funding.
Seemingly prompted by an unknown substance secreted by fish, the aggressive creature swims into action. It sends neurotoxins into the water and air, paralyzing a fish’s nervous system, and causing it to gasp for air at the surface. Eventually the fish suffocates. The killer dinoflagellate then attaches itself to the fish and begins sucking away at its flesh. This macabre scenario may help solve several sea mysteries, such as why fishermen report seeing "fish walks" (fish trying to leave the water) and pools of dead fish with holes eaten through them.
Whether humans are affected by the dinoflagellate’s toxin remains to be seen. Researchers think it’s unlikely eating fresh fish are in danger, but anyone with frequent exposure to the creature could be in peril. Several researchers working with the algae have reported bouts of memory loss and disorientation.
To understand the killer algae further, scientists must fully characterize their toxin and determine what stimulates them to attack. They also need to know if the algae are hurting fish populations, and whether pollutants make them more likely to attack.

Researchers think that it is ______.

A. safe to eat fresh fish

B. dangerous to get close to the algae
C. safe to be near the algae

D. dangerous to expose the algae

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属于配伍禁忌的配伍关系是()

A.相反、相须

B.相畏、相杀

C.相恶、相反

D.相杀、相反

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