皮肤接触水后出现荨麻疹首先考虑（）。
A.胆碱能荨麻疹
B.接触性荨麻疹
C.水源性荨麻疹
D.寒冷性荨麻疹
E.热性荨麻疹
参考答案：C
--Did you listen to the speech?
--- No, we ______ it. But we had a lot of traffic on our way.
A．could have attended
B．must have attended
C．could attend
D．shouldn't have attended
新胶轮车在行驶（）km并待柴油机完全冷却后，应将气缸盖螺母按规定次序和规定拧紧力矩，由中间向前后两端逐一拧紧。
A、300
B、400
C、500
D、600
