硫化物常以颗粒状残留于钢中，热轧时与钢一起被压延成带状夹杂，造成轨头或轨腰水平裂纹和（）。
A、分层
B、核伤
C、裂纹
D、气孔
参考答案：A
—Mr Wang was caught in a snowstorm yesterday.
—I have known that，and_______his new car was completely destroyed.
A．hopefully
B．fortunately
C．thankfully
D．unfortunately
轨梁厂800轧机生产钢轨时使用的轧辊属于（）
A.球墨铸铁轧辊
B.无限冷硬铸铁轧辊
C.锻钢轧辊
D.合金轧辊
