稀介质净化回收流程有()。
A、A+B组合
B、分级磁选
C、浓缩磁选
D、直接磁选
参考答案:A, C, D
-Is your sister at home, Dennis?
-No, she isn't. I think she _ _ the piano in Anna's living room. [ ]
A. can play
B. could be playing
C. had played
D. plays
下面不属于定性描述的是()
A.闻起来
B.看起来
C.感觉起来
D.1m