离心泵的工作特点是流量（）。
参考答案：比较小
So many people violate traffic regulations that we ____ put too much emphasis on the importance of traffic safety.
A．must not
B．should not
C．need not
D．cannot
用于亚硝酸盐中毒的治疗
A．亚甲蓝B．阿托品C．二巯基丙醇D．二乙烯三胺五乙酸三钠钙
