离心式压缩机常用的调节方法有哪几种?
参考答案:
(1)出口节流;
(2)进口节流;
(3)采用可调节的进口导叶;
(4)采用可调节的扩压器叶片;
(5)改变转速。
27. I wonder whether the police ______ that lost child or not
A.have found
B.has been found
C.have been found
D.has found
钙化性病变的胸片表现特点是()
A.云絮状浅淡模糊影
B.条索状密度增高影
C.边缘清楚致密影,密度比肋骨低
D.边缘清楚致密影,密度比肋骨高
E.肺透亮度增加,局部肺纹理缺如