在同一管径,同样的操作条件下,()节流装置压力损失最大.
A.喷嘴
B.文丘利管
C.孔板
D.均速管
参考答案:C
.When _____ if he had seen her, Mattew just shook his head.
A.asking
B.asked
C.being asked
D.being asking
其他条件不变的情况下,短期内,主要原材料价格的上升会引起经济繁荣。