流体在管道中作稳定流动时,同一时间内流过管道每一截面的流量相等。
参考答案：对
The sample mean is a consistent estimator of the population mean because the:（）
A. expected value of the sample mean is equal to the population mean.
B. sampling distribution of the sample mean has the smallest variance of any other unbiased estimators of the population mean.
C. sample mean provides a more accurate estimate of the population mean as the sample size increases.
证券经纪商是证券市场的中坚力量。( )
