Shells were used as money in these tribes________recent times.

Shells were used as money in these tribes________recent times.
A、before
B、since
C、after
D、until
【正确答案】：D
【题目解析】：该题考查until的用法。until在这里是介词，意为“到……时候为止”，如I watched TV until she came back. 我看电视一直看到她回来。本题的句意为“直到最近在这些部落贝壳都是作为钱使用的。”另外还要注意not…until…结构，意为“直到……才……”，例如：She didn’t leave until the rain stopped.直到雨停她才离开。