关于伤寒沙门菌，错误的是
A．革兰染色阴性
B．均为显性感染
C．抗原结构复杂
D．不产生外毒素
E．感染后无并发症
参考答案：B
— At the end of the day we can gather our guests to enjoy fine wine.
— You seem to be getting off the point. How is that _______ to this discussion?
A．suitable
B．tentative
C．parallel
D．relevant
A．时刻t线圈中电流的瞬时值icosωt
B．线圈中电流的有效值I
C．线圈中电流的有效值I=
D．线圈消耗的电功率P
cosωt
