Because many of the minerals found on the ocean floor are still ___on land, where mining is relatively inexpensive,mining the ocean floor has yet to become a ___enterprise.
A.scarce..common
B.accessible..marginal
C.unidentified..subsidized
D.conserved..public
E.plentiful..profitable
答案选E,has yet to 翻译成“还没有”吗?可是人家没有否定啊。。。