单项选择题

The amount left was estimated to be half again as much as all the copper that has been mined.()

A.当时计算余下的数量是已开发铜总量的一倍半。
B.当时估计剩下数量是已开采铜总量的半倍。
C.当时估计剩余数量是已开采铜总量的一倍半。
D.剩下的数量被评估为是矿山铜总量的半倍。