铸件尺寸公差及机械加工余量等级有（）级。
A.5
B.10
C.15
D.20
参考答案：B
_____ seemed as if nobody knew anything about the matter.
A．This
B．That
C．It
D．One
足太阳膀胱经的穴位数为（）
A.45个
B.67个
C.44个
D.69个
E.43个
