造成根管器械折断的原因如下，除外
A．过度用力扭转
B．根管锉质量缺陷
C．根尖预弯
D．镍钛器械金属疲劳
E．根管弯曲度过大
参考答案：B
一个数a的8倍，减去这个数a的6倍，差是19。求这个数a
[听力原文] 6-7
M：Who do you work for
W：(6) ABC Company．
M：They’re in the dress business，aren’t they
W：That’s right．I’m the secretary to the General Manager．What about you
M：(7) I work for IBM．
W：(7) So you’re in computers.
M：Yes，I’m a product manager．
W：What are you working on at the moment
M：I can’t give you all the details．because it’s a secret．But we are developing a new product for the
What does the man deal with（）
A．Dress.
B．Computers.
C．Shoes.
D．Engines.
