在碳素工具钢中加入适量的合金元素，如：锰、铬、钨、硅等，制成（）钢。
A.高速钢
B.硬质全合金
C.合金工具
D.陶瓶
参考答案：C
______ to be a football player of the school team, the boy made up his mind to train even harder.
A．Having not chosen
B．Being not chosen
C．Not having been chosen
D．Having not been chosen
冷滑列车采用内燃机车牵引时怎样编组？
