China supplies more than 90 percent of t
题型：选择题
问题：
China supplies more than 90 percent of the world's rare earth metals, but its reserves only _________
about one-third of the world's total. [ ]
A. take up
B. make up
C. build up
D. polish up
China supplies more than 90 percent of the world's rare earth metals, but its reserves only _________
about one-third of the world's total. [ ]
A. take up
B. make up
C. build up
D. polish up