直线的投影变换中，一般位置线变换为投影面平行线时，新投影轴的设立原则是新投影轴（）直线的投影。
A、垂直
B、平行
C、相交
D、倾斜
参考答案：A
Would you please tell me _____? [ ]
A. what was her name
B. what her name was
C. what is her name
D. what her name is
流体微团的速度，密度和压力等参数随时间变化的流体称为什么流体？
