化妆品中所含的亚硝基二乙醇胺属于（）
A.无毒类物质
B.高毒类物质
C.微毒类物质
D.致突变性物质
E.致癌性物质
参考答案：E
________ with her work, she didn't even notice the heavy snowfall outside the window.
A．Occupying
B．To be occupied
C．Having occupied
D．Occupied
常用钻床有哪几种其共同特点是什么
