A small car is big enough for a family of three you need more space for baggage.
A. once
B. because
C. if
D. unless
网友回答
A. once
B. because
C. if
(答案→)D. unless
解析：题意是“如果你不需要更多的空间来放行李，那么一辆小车对一家三口来说就足够了。”unless引导条件状语从句，在此相当于if you don’t need more space for luggage.