对于普通手机带电池自由跌落试验的高度是多少（）。
A.0.8m
B.1.0m
C.1.2m
D.1.5m
参考答案：B
The boys _______ playing football now. [ ]
A. isn't
B. aren't
C. don't
D. doesn't
会议需果盘、点心服务时，应在会前（）到位。
A.4小时
B.3小时
C.2小时
D.1小时
