数字广播不可直接传递（）信号。
A、数字信号
B、图文数字
C、音频数字
D、视频模拟
参考答案：D
Having checked the doors were closed, and _____all the lights were off, the boy opened the door to his bedroom.
A．why
B．that
C．when
D．where
什么是高温作业？有哪几种类型？
