热烧结矿的筛分，国内多采用筛分效率高的热矿振动筛。
参考答案：对
a3（b-c）+b3（c-a）+c3（a-b）
Those overseas students volunteer 10 hours each week in Paris ________ free food and accommodation.
A．in search of
B．in contact with
C．in case of
D．in exchange for
