When she arrived,she found that the letters____(take) away
问题描述：
When she arrived,she found that the letters____(take) away
答
has been taken
当她到达时，信已经被拿走了。现在完成时
答
was taking
答
had been taken 发生在found主语动作之前，所以应该用过去完成时，信被带走是被动式
答
had been taken
答
had been taken.
本句话意思：她到的时候,她发现信件已经被带走了.
信件是被带走,所以应该用被动,加之take away这个动作发生在arrived的之前,所以是过去的过去,应该用过去完成时.
综上,答案：had been taken.
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答
taken
信是被拿走了，所以用过去分词，表示被动完成的动作
答
had been taken, 这个动作发生在found主语动作之前，所以应该用过去完成时，信被带走是被动式