向转炉中加入()可以暂时提高炉渣氧化性。
A.萤石
B.活性石灰
C.矿石
参考答案:C
13. Every time the father comes into his room, the boy pretends ______ earnestly.
A.reading
B.to be reading
C.to be read
D.to have read
允许速度υmax≤120km/h线路,正线及到发线除外的其他线,两股钢轨水平,较标准的静态允许偏差为()。
A、3mm
B、4mm
C、5mm
D、6mm