_______ you return those books to the library immediately you wi

_______ you return those books to the library immediately you will have to pay a fine.
A、Until
B、If
C、Unless
D、Provided
【正确答案】：C
【题目解析】：译文：除非你立即归还图书馆的书，否则你将不得不付罚金。本题考查连词用法。C项的Unless意为“除非"，最合题意。答案为C。