通信工程师英语高级题

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(       )     
_________the receiving end of a synchronous serial data link
，
the receiver continually monitors the line _________a start bit.
A. On，looking                              B. Within，look for
C. In, look at                                  D. At，looking for
(       ) As companies realized they could save money and gain productivity by _________networking technology, they added networks and expanded _________networks almost as rapidly as new network technologies and products could be introduced.
A. use, exist                                    B. using, existing
C. to use, to exist                             D. used, existed