题目内容
在每组第二个句子的空白处填入适当的词，使句意与第一句相符：We've never heard him sing, have we?
He's never been heard ______, has he?
答案：to sing
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题目内容
在每组第二个句子的空白处填入适当的词，使句意与第一句相符：We've never heard him sing, have we?
He's never been heard ______, has he?