丁级测绘单位注册资金不低于()
A.30万
B.40万
C.50万
D.60万
参考答案:C
—______ you ______ anything in that store?
—No, I ______, but Jim ______.[ ]
A. Did; bought; didn't; bought
B. Did; buy; didn't; bought
C. Did; bought; didn't; buy
D. Did; buy; didn't; did
简述矿物磁性的分类,及其分选特点。