题干
只要你提前三个月预订，飞往悉尼的票价就会减半。
The air ticket to Sydney will be half price _______________________ it three months earlier.
答案(点此获取答案解析）
as long as/ if you book
只要你提前三个月预订，飞往悉尼的票价就会减半。
The air ticket to Sydney will be half price _______________________ it three months earlier.
as long as/ if you book
