[单选题][单选题] The air in the house does not remainfresh very long. It′s because
Athe fresh air can't come into the house
Bthere is only a little fresh air comingin a little waste going out
Cthe air in the house can't remain fresh
Dthe house gives off wastes
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答案解释:
根据常识判断,室内空气不新鲜是由于不流通所致