作烤瓷冠牙体预备时要求切缘斜面与牙长轴呈（）
A.5°
B.15°
C.30°
D.45°
E.60°
参考答案：D
----I have a piece of good news for you. You’ve been elected as monitor in our class.
---- ______ That’s great!
A．Congratulations!
B．Good idea!
C．Oh, really?
D．What about you?
一般情况下，烤烟下部叶的身份为（）
A、薄
B、薄至稍薄
C、中等至厚
D、稍厚
