债券的收益率随着债券期限的增加而减少，这种债券的曲线形状被称为( )收益率曲线类型

---Mary has a very low opinion of George.

---It can' t be any worse than ____ of her.

A．he

B．his

C．him

D．he does

Mr.Smith        an imprtant part when he gave the lecture last Friday .

A．left out

B．picked out

C．let out

D．took out

“劝百讽一”

由几个连续的C-n标准帧组成的调整帧称为复帧，目的是什么？

天桥、跨线桥靠近跨越接触网的地方，必须设置（）以屏蔽感应电流。