The new system needs to be in operation for five months it can be updated.A. asB. whileC

发布时间：2020-08-17 10:03:57

The new system needs to be in operation for five months      it can be updated.
A. as
B. while
C. before
D. once

网友回答

A. as
B. while
(答案→)C. before
D. once
解析：C考察状语从句。本句的before用语肯定句中，强调主句动作持续的时间比较长，意为：要多多久….才。故C正确。
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