加减-阴煎主要适用于（）
A.肾气亏损证闭经
B.阴虚血燥证闭经
C.肝肾亏损证闭经
D.阴虚血热证闭经
E.湿热蕴结证闭经
参考答案：B
Many Chinese find ___necessary for them to have a good command of English.[ ]
A．this
B. that
C. it
D. what
A special device that，when fitted into the rotary table，transmits torque to the kelly and simultaneously permits vertical movement of the kelly to make the hole is called a（）.
A.master bushing
B.kelly slips
C.kelly bushing
D.rotary bushing
