问题描述：
Eva decided to take a second course since she ____ the first one.
A.has completed B.is completed C.had completed D.will complete 我知道选C但需要解释为什么不选A?
A.has completed B.is completed C.had completed D.will complete 我知道选C但需要解释为什么不选A?
问题解答：
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