题目内容：
选词填空。Melinda and Helen are talking about 回答
, a piece of office equipment. Actually, it has 回答
to do with pigeons, and it is used to store 回答
in a systematic way. Each pigeon hole is a 回答
that is clearly 回答
. When the papers are 回答
in current use, they can be 回答
to the long-term 回答
★pigeon hole: a small open space in a desk, cabinet, or wall for keeping letters or papers.
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