液化气储罐应设放散管，管口应高于操作平台2米以上且应高出地面多少米以上？
A.2米
B.4米
C.5米
参考答案：C
The risk-free interest rate is 5 percent, and the return on market portfolio is 8 percent. A stock with a beta of 0. 5 that has an estimated rate of return of 7 percent is most likely:（）
A. overvalued.
B. undervalued.
C. correctly valued.
发电机同期并列时，与系统的频率允许有5%~10%的误差。（）
