___________ is the shirt? Twenty yuan.[ ]
A. How many
B. How much
C. How old
答案:B
提出龋病三联因素概念的是()
A.Keyes
B.G.V.Black
C.Miller
D.Moore
E.Corbett
短路电流计算求出最小短路电流值,作为选择熔断器、整定继电保护装置和校验电动机起动的依据。( )