如果已知管路上任意两点的压强，就可以根据压强大小确定流动方向。
参考答案：错
-- I enjoyed the performance very much.
-- Yes, it was really good. I think ________ boy in white was the best actor.
A．a
B．an
C．the
D．/
常见的需求分析方法有______和面向对象的分析方法。
