正态曲线下面积有一定的规律,μ±1σ的面积占总面积的()
A.50.5%
B.55.2%
C.62.8%
D.68.2%
E.69.2%
参考答案:D
Before testing this method on patients, Dr. Baker had tests for two years
on three hundred dogs.
A.found out
B.helped out
C.worked out
D.carried out
离心式压缩机中采用()效率最高。
A、前弯叶轮
B、后弯叶轮
C、径向叶轮
D、都一样