离心式风机的调节方式不可能采用()。
A、节流调节;
B、变速调节;
C、动叶调节;
D、轴向导流器调节。
参考答案:C
I can't understand why you all ________ think that I did it. [ ]
A. shall
B. will
C. can
D. should
实验室有失去标签的盐酸、碳酸钠、硫酸、氢氧化钾和硝酸钾五瓶溶液.为把它们区分开来,所加试剂及先后顺序合理的一组是( )
A.氯化钡溶液、稀硝酸、石蕊试液
B.稀硝酸、石蕊试液、硝酸银溶液
C.石蕊试液、稀硝酸、硝酸银溶液
D.稀硝酸、酚酞试液、硝酸银溶液