I’ll go to your party you promise me that you will invite our class advisor.
A. if only
B. only if
C. unless
D. since
网友回答
A. if only
(答案→)B. only if
C. unless
D. since
解析：这题考查连词的用法：if only但愿，only if只有如果…unless除非，since自从，句意是：只有你答应邀请我们班的导师，我才去参加你的聚会。选B。