I enjoy fresh air so always sleep with the window open ______ it is really cold． A．unless B．when C．i...
2023-01-03 18:21:50 194次 2014-2015学年山东省学业水平模拟考试英语试卷（解析版） 单项填空 反馈错误 加入收藏 正确率 : 100%
题目内容：
I enjoy fresh air so always sleep with the window open ______ it is really cold．
A．unless B．when C．if D．Since
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