What does Maria do with her sister usually?
A. They go for a coffee together.
B. They have lunch at the town.
C. They watch a movie once a month.
D. They have a takeaway toghther every Friday.
查看答案
What is true about the man they talk about?
A. He is an interesting guy.
B. He like sports.
C. He does a lot of travelling.
D. All above.
浮选泡沫产品在离开浮选工艺，进入浓缩机后，如果泡沫依然存在，为了使得浓缩过程的顺利进行，我们需要加入下列哪种药剂( ）
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