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问题 单项选择题

未曝光的AgBr在显影液中不被还原的原因是（）。

A.由于Br-离子被吸附在AgBr表面，排斥了显影剂负离子对未曝光的AgBr的还原作用

B.由于未曝光的AgBr晶体中含Ag+的质点较小，催化作用弱

C.由于显影温度、时间、pH值适当

D.A、B和C

答案

参考答案：A

单项选择题

Joshua Douglas, CFA, is interested in the relationship between the stock prices of two companies, Sonata Inc. and Prius Inc. After downloading a time series of stock prices for each company, Douglas concludes that Sonata Inc. has a variance equal to 25.0 percent and Prius has a variance equal to 20.0 percent. If the covariance between the two stocks is -0.10, the correlation coefficient is:（）

A. negative, and indicates that a 1.0% increase in the price of Sonata would be accompanied by a 2.0% decrease in the price of Prius.

B. negative, and indicates that a 10.0% increase in the price of Sonata would be accompanied by a 4.5% decrease in the price of Prius.

C. positive, and indicates that a 1.0% increase in the price of Sonata would be accompanied by a 2.0% increase in the price of Prius.
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判断题

吊脚楼可以起到通风避潮和防止野兽侵袭的作用。( )
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