U形管压力计标尺的零点设在()

(A)温度、压力、流量;
(B)压力、流量、液位;
(C)流量、压力、流速;
(D)温度、压力、流速

(A)环室取压和法兰取压;
(B)环室取压和角接取压;
(C)角接取压和法兰取压;
(D)法兰取压和压力表取压

(A)2min内;
(B)数分钟内;
(C)10min;
(D)30min