前颅底平面是指（）。
A.SN平面
B.FH平面
C.N～Bolton平面
D.N～Ba平面
E.以上都不是
参考答案：A
— Is the price of the backpack very______?
— No, it ______me only twenty yuan.
A．high;spent
B．expensive;takes
C．high;cost
D．cheap;spends
I have bought two ball pens ,______ writes well.
A．none of them
B．neither of them
C．neither of which
D．none of which
