XONIXOFF是(1)中采用控制字符来进行(2)控制的一种方案,当通信线 路上的(3)发生过载时,便向_(4)发送一个(5),以使发送方暂停发送数据 (1)A.面向字符的异步通信 B面向比特的异步通信 C.面向字符的同步通信 D.面向比特的同步通信 2)A.通信 B.流量 C.差错 D.流量与差错 (3)(4)A发送方B.接收(发送)方C发送(接收)方D接收方 (5)AXON B XOFF C.1 D.0 答案: ABDAB Error-checking schemes determine whether (1) has become corrupt otherwise damaged while traveling from the source to the destination Error checking is implemented at (2)of the OSI layers One common error-checking scheme is (3),which detects and discards corrupted data. (4)fuctions(such a data retransmission ) are left to higher-laye protocols. A CRC value is calculated at (5).The destination device compares the two values to determine whether errors occurred during transmission (1)A. receiving data B transmitted data C transmitting data D received data (2)A.several B two C three D. four (3)A Parity check B. Hamming Codes C. Single-P heck D. CRC (4 )A. Error-checked B. Error-checking C. Error-correction D. Error-controlling (5 )A. the source and destination device B. the source or destination device C the destination device D. the source device 答案: BADCAXON/XOFF 是_(1)_中采用控制字符来进行_(2)_控制的一种方案，当通信线 路上的_(3)_发生过载时，便向_(4)_发送一个_(5)_，以使发送方暂停发送数据。 (1)A.面向字符的异步通信 B.面向比特的异步通信 C.面向字符的同步通信 D.面向比特的同步通信 (2) A. 通信 B.流量 C. 差错 D.流量与差错 (3) (4) A.发送方 B.接收（发送）方 C.发送（接收）方 D.接收方 (5)A.XON B.XOFF C.1 D.0 答案：ABDAB Error-checking schemes determine whether _(1)_ has become corrupt or otherwise damaged while traveling from the source to the destination . Error checking is implemented at _(2)_ of the OSI layers. One common error-checking scheme is _(3)_,which detects and discards corrupted data. _(4)_fuctions (such a data retransmission)are left to higher-layer protocols.A CRC value is calculated at _(5)_.The destination device compares the two values to determine whether errors occurred during transmission. (1)A. receiving data B.transmitted data C.transmitting data D.received data (2) A.several B.two C.three D.four (3) A.Parity check B. Hamming Codes C. Single-Parity check D.CRC (4)A.Error-checked B. Error-checking C.Error-correction D. Error-controlling (5)A.the source and destination device B. the source or destination device C.the destination device D. the source device 答案：BADCA