问题
单项选择题
NTSC制式的特点是用两个色差信号（R-Y）和（B-Y）分别对频率相同而相位相差（）度的两个副载波进行正交平衡调幅，再将已调制的色差信号叠加，穿插到亮度信号的高频端。
A.30
B.45
C.60
D.90
答案
参考答案：D
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NTSC制式的特点是用两个色差信号（R-Y）和（B-Y）分别对频率相同而相位相差（）度的两个副载波进行正交平衡调幅，再将已调制的色差信号叠加，穿插到亮度信号的高频端。
A.30
B.45
C.60
D.90
参考答案：D
My name Bill. I’m English boy. I’m twelve. I’m a middle school student. Lin Hai is my . We’re in the same class. Here is a picture his family. Look, this is his . He is a policeman(警察). His is a teacher of English. She is a good teacher. Lin Hai has sisters. are twins(双胞胎). Their are Fangfang and Yuanyuan. They have a cat. We are good , too.
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