西亚是________教和_________教的发源地。
基督；犹太
m段流水线每段时间均为△t，则最大加速比=（）。
An analyst does research about correlation. In a portfolio of two risky securities, the portfolio risk is maximized when the two securities are.（）
A. uncorrelated.
B. perfectly positively correlated.
C. perfectly negatively correlated.
