可消除检测体系或样本混浊的方法是（）
A.单试剂双波长法
B.单波长双试剂法
C.双波长法
D.双试剂法
E.双波长双试剂法
参考答案：A
— You shouldn't have talked back to our teacher like that. It was awfully impolite.
— You are right. I ______ crazy at that moment.[ ]
A. must be
B. could have been
C. must have been
D. should have been.
在电气化铁路区段，任何人（）机车、车辆顶部。
A.不准攀登
B.进行作业
C.坐立
D.站立
