When last valuable, those books enjoyed great success．A.findingB.foundC.being fo
来源：网络
时间：
推荐文章
When last ________ valuable, those books enjoyed great success．
A.finding
B.found
C.being found
D.to be found
试题答案
B
解析：分析句子的结构和逻辑关系，可以把when last…看成是一个省略句，相当于：When those books were found valuable，这里books与found是主谓关系，所以用过去分词。