The doctor suggests that I should sleep with the window open选哪个?

问题描述:

The doctor suggests that I should sleep with the window open选哪个?
The doctor suggests that I should sleep with the window open() it’s very cold.
A、if
B、unless
C、when
D、since

选择B,表示除非的意思
本句的意思是,医生建议我除非天气很冷,否则就应该开窗睡觉!