To keep the air fresh during the night, I often sleep with the windows on ______

题干

To keep the air fresh during the night, I often sleep with the windows on ________ it’s really cold.

A．unless

B．if

C．because

D．when

上一题下一题 0.65难度单选题更新时间:2014-11-19 06:48:57

小学学科试题库

初中学科试题库

高中学科试题库