Pure feldspar is a colorless,transparent mineral,but impurities commonly make it opaque and colorful.
A.truly
B.rapidly
C.periodically
D.frequently
正确答案是D
Pure feldspar is a colorless,transparent mineral,but impurities commonly make it opaque and colorful.
A.truly
B.rapidly
C.periodically
D.frequently
正确答案是D