应用最为广泛的积温有（）。
A、活动积温
B、无效积温
C、净效积温
D、有效积温
参考答案：A, D
They hardly watch TV on school nights, ________? [ ]
A. will they
B. aren't they
C. do they
D. didn't they
普通WLAN业务资费包括哪些？
