In the following essay，each blank has four choices．Choose the most suitable onefrom the follow choices and write down in the answer sheet．
Open Shorest Path First(OSPF)is a
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routing algorithm that
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work doneon the OSI IS．IS intradomain routing protocol．This routing， as compared to distance-vectorrouting，requires
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processing power．The
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algorithm is used to calculate routes．OSPF routing table updates only take place when necessary，
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at regular intervals．
供选择的答案
A．but rather B．rather too C．rather than D．rather that
