当切削力大于镗杆所受重力时，切削力都可以推动镗杆紧贴在与切削位置（）方向的导向套表面上。
A.相同
B.相反
C.垂直
参考答案：B
As technological advances put more and more time between early school life and the young person''s final access to specialized work, the stage of ________becomes an even more marked and conscious period.
A．adolescence
B．adjacency
C．advantage
D．adventure
引起缺铁性贫血的主要原因是
A．慢性失血B．妇女妊娠或哺乳C．青少年生长发育D．食物中供铁不足E．胃大部切除术
