In summer milk will quickly go bad____

试题详情及答案解析

In summer milk will quickly go bad_____ it is put into a fridge.

A．though	B．unless
C．because	D．once

答案：B

试题分析:句意：在夏天，牛奶如果不放进冰箱很快就会变质。A．though尽管；B. unless 除非，如果不； C. because因为；D. once立刻，马上。由语义可知选B。
考点：考查连词用法。