问题
单项选择题
使用过滤式自救器时，灾区内空气中的氧气浓度不得小于（）%。
A.12
B.18
C.20
答案
参考答案：B
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使用过滤式自救器时，灾区内空气中的氧气浓度不得小于（）%。
A.12
B.18
C.20
参考答案：B
An analyst does research about capital asset pricing model and gathers the following information:
| Estimated rate of return for a stock | 12.0% |
| Expected rate of return for the market risk premium | 9.5% |
| Risk-free rate of retum | 3.5% |
A. overvalued.
B. properly valued.
C. undervalued because the required rate of return for the stock is greater than 9.5%.