在煤与瓦斯突出矿井的煤巷中能不能使用扒矸机？
参考答案：
不能
— We've only got this small bookcase. Will that do?
— No, ________ I am looking for is something much bigger and stronger. [ ]
A. who
B. that
C. what
D. which
混合浮选时，矿浆中的（）对浮选有干扰和影响。
A、Ca2+
B、Mg2+
C、Na+
D、Cu2+
