[9] Failure never makes people pleasurable,but it can make a positive contribution to your
问题描述：
[9] Failure never makes people pleasurable,but it can make a positive contribution to your
life ______ you learn to use it.
A.since
B.once
C.until
D.unless
翻译并详细分析.
答
我怎么感觉是b呢?大概意思是：失败从来不会给人带来愉快（快乐）,但是却能够给你的人生造成积极的影响（一旦你学会如何使用它）.