选用你认为最合适的刀具材料。高速精车钢件用（）；拉削的拉刀用（）。
参考答案：硬质合金、高速钢
______, he talks a lot about his favorite stars after class．
A．Being a quiet student
B．Quiet student as he may be
C．Quiet as he may be a student
D．As he may be a quiet student
可改变宿主对菌斑反应的因素有
A．激素水平B．刷牙习惯C．无牙龈萎缩D．咬硬物E．洁治
