问题
单项选择题
当局间传输采用PCM中继时，采用（）线路信令方式。
A.模拟
B.直流
C.数字
D.记发器
答案
参考答案：C
搜题请搜索小程序“爱下问搜题”
当局间传输采用PCM中继时，采用（）线路信令方式。
A.模拟
B.直流
C.数字
D.记发器
参考答案：C
| 根据句意,用方框内词汇填空,使句子完整、正确. | |
2. As the monitor, you must do your _______ and report the truth to the teacher. 3. We found the holiday ________ because of the bad weather. 4. It's not polite to ______ others in trouble. 5. Many students have to _______ the meaning of this word in the dictionary. |