TRC的中文名称是（），有（）、脉冲频率调制、混合调制三种调制方式。
参考答案：时间比例控制；脉冲宽度调制
—What does your English teacher look like?
—_________. [ ]
A. He is a good teacher.
B. He is friendly.
C. He is tall with a round face.
D. He is a good friend.
700hPa对应的高度大约为（）
