调节汽阀的重叠度为什么不能过大或过小?
参考答案:
重叠度过小,不能消除曲线中的曲折部分;重叠度过大,阀门的节流损失增加,机组的经济性降低。一般调节汽阀的重叠度为10%。
—Do you think he will do me a favor?
— As far as I know, he is the last one to help others. He______be prepared to give you a hand, though.
A.might
B.must
C.can
D.should
下列不属于图形出图方向的是()。
A.纵向打印
B.横向打印
C.定向打印
D.反向打印