Mike is Mary's deskmate. He is sitting beside _____________. [ ]
A. he
B. her
C. him
答案:B
采用抗原抗体反应对传染病进行诊断,抗原与抗体的比例为()。
A.3:1
B.1:3
C.1:1
D.2:3
E.3:2
试述冷升水系统的流程?