问题描述：
请问一道英语选择题2012.12.31.31
26、41.When climbing the hill,John was knocked unconscious by an ______ rolling stone.
A.untouched
B.unfamiliar
C.unexpected
D.unbelievable
这道题怎么选,怎么翻译,为什么
26、41.When climbing the hill,John was knocked unconscious by an ______ rolling stone.
A.untouched
B.unfamiliar
C.unexpected
D.unbelievable
这道题怎么选,怎么翻译,为什么
问题解答：
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