a.数据链路面向字符的特征b.在字符后所收到的奇偶校验位 被称为字符的比特组 答案:c 60. A clock generated locally by the receiver a.最为流行的串行接口b.由接收机本地产生的时钟 C.发送器和接收器的时钟 答案:b III.选择合适的答案 1. Furthermore, we shall prove that a minimum theoretical sampling frequency of order 6 8KHz is required() a voice channel()the range 300 Hz to 3. 4KHz a convey, occupy b. to convey, occupying c. conveying, occupied d. convey, to occupy 答案:b 2. For example, the signal( from a satellite,()in far outer space, is very weak. a. received, located b. receive, locate c. receiving, locating d. to receive, to located 答案:a 3. If we consider binary transmission, the complete information about a particular message will always( by simply( )the presence or absence of the pulse. a. obtain, detect b. be obtained, detecting obtained, detected d. obtaining, detected 答案:b 4. There is a inherent advantage for() noisy environments by() digital transmission a. overcoming, choose b. overcome, choosing c. overcome, choose d. overcoming, choosing 答案:d 5. Each voice channel has a separate coder, the unit( converts sampled amplitude values to a set of pulse; and decoder, the unit( )performs the reverse operation. a, who, who b. when. when c. where. where d. that, that 答案:d 6. The problem is easily overcome by( )a frame format, where at the start of each frame a unique sequence of pulses is placed () the start of the frame a. specify, identify b. specifying, so as to identify c. specified, identified d. specify, identifying 答案:b 7. It was( ) in 1969, when the U. S. Department of Defense establisheda. 数据链路面向字符的特征 b. 在字符后所收到的奇偶校验位 c. 被称为字符的比特组 答案：c 60． A clock generated locally by the receiver a. 最为流行的串行接口 b. 由接收机本地产生的时钟 c. 发送器和接收器的时钟 答案：b III.选择合适的答案 1.Furthermore, we shall prove that a minimum theoretical sampling frequency of order 6.8KHz is required ( ) a voice channel ( ) the range 300 Hz to 3.4KHz. a. convey , occupy b. to convey, occupying c. conveying , occupied d. convey, to occupy 答案：b 2. For example, the signal ( ) from a satellite, ( ) in far outer space, is very weak. ａ. received, located b. receive, locate c. receiving, locating d. to receive, to located 答案：a 3. If we consider binary transmission, the complete information about a particular message will always ( ) by simply ( ) the presence or absence of the pulse. ａ.obtain, detect b. be obtained, detecting c. obtained, detected d. obtaining, detected 答案：ｂ 4. There is a inherent advantage for ( ) noisy environments by ( ) digital transmission. ａ．overcoming, choose b. overcome, choosing c. overcome, choose d. overcoming , choosing 答案：d 5. Each voice channel has a separate coder, the unit ( ) converts sampled amplitude values to a set of pulse; and decoder, the unit ( ) performs the reverse operation. ａ．who, who b. when, when c. where, where d. that , that 答案：d 6. The problem is easily overcome by ( ) a frame format, where at the start of each frame a unique sequence of pulses is placed ( ) the start of the frame. a. specify, identify b. specifying, so as to identify c. specified, identified d. specify, identifying 答案：b 7. It was ( ) in 1969, when the U.S. Department of Defense established