题目选项分析

Between 14,000 and 8,000 B.C. the ice cap that covered northern Asia, Europe, and America began to melt, uncovering vast new areas that were to be occupied by migrating peoples moving northward.

Between 14,000 and 8,000 B.C. the ice cap that covered northern Asia, Europe, and America would begin to uncover, through melting, vast new areas for occupation by migrating peoples moving northward.