Keep ________! Don't make noise in the hospital. [ ]
A.quiet
B.loud
C.noisy
D.low
答案:A
PH值越小表明溶液()
A.氢离子浓度越小
B.酸性越强
C.酸性越弱
D.碱性越强
更换调速级喷嘴组,对新喷嘴组应做哪些核查工作?