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问题 单项选择题

求气体的密度时ρ=Pm/RT式中T的单位为K，M的单位为Kg/kmol，R为8.314KJ/Kmolk，P的单位为（）。

A.atm

B.Pa

C.mmHg

D.KPa

答案

参考答案：D

单项选择题

关于流脑的流行病学特点，正确的是

A．病人是重要传染源

B．传播途径主要经飞沫传播

C．细菌毒力强，故间接传播亦重要

D．本病发生有严格季节性(冬春季)

E．感染后仪产生对本群细菌的免疫，无交叉免疫
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单项选择题

Which of the following statements about the risks associated with investing in bonds is least accurate （）

A. Credit risk is the likelihood that an investor will be unable to sell the security quickly and at a fair price.

B. Reinvestment risk is the uncertainty about the rate at which cash flows from the security can be reinvested.

C. Volatility risk is the risk that the price of a bond with an embedded option will decline when expected yield volatility changes.
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