刃带处副切削刃的（）为零值，造成副后刀面与孔壁间的摩擦加大。
A.副后角
B.主后角
C.顶角
D.前角
参考答案：A
He liked to go to dances and parties, ______ he could have a good time just sitting and watching.
A．where
B．when
C．which
D．why
《内经》理论体系的核心是（）
A.阴阳学说
B.养生学说
C.病因学说
D.藏象学说
E.精气神学说
