根据工作频段可以将电子标签划分为（）等不同种类。
A.低频
B.高频
C.超高频
D.微波
参考答案：A, B, C, D
—Why didn’t you put your cellphone in your overcoat pocket?
—I _____, but I was afraid it would be stolen.
A．had put
B．put
C．would have
D．could have
用四舍六入五单双法，将指定修约间隔为1的拟修约数值15.4546进行修约的正确方法是（）。
A．15.4546→15
B．15.4546→15.455→15.5→16
C．15.4546→15.5→16
