关于比摩阻R,论述正确的有()。
A.比摩阻即每米管长的沿程压力损失
B.比摩阻即每米管长的压力损失
C.比摩阻与流量无关
D.比摩阻与管径无关
参考答案:A
If you receive a bunch of roses on Valentine's Day, Do you know what hidden meaning is
_____ to it? [ ]
A. put
B. introduced
C. attached
D. tied
函数f(x)=log2(x-x2)的单调递减区间是______.