粘性流体测压管水头线的沿程变化是:()
A.沿程下降
B.沿程上升
C.保持水平
D.前三种情况均有可能
参考答案:D
解析:测压管水头线升降与流速水头有关。
—Isn't it a surprise that I happened to meet Francis Mafhews at the Christmas party last week?
—If my memory serves me correctly, you ____ each other for exactly two years. [ ]
A. hadn't seen
B. haven't seen
C. didn't see
D. don't see.
CD-ROM光盘的外缘有5mm的范围因记录数据困难,一般不使用,故标准的播放时间为60分钟。请计算模式1情况下光盘存储容量是多少?