测微准直望远镜，用（）为基准安装定位，可以确定光轴的位置。

A.物镜

B.反射镜

C.外镜管轴线

D.透镜

Yield to call is a less conservative yield measure than the yield to maturity whenever the price of a callable bond is quoted at a value:（）

A. equal to par value less one year's interest.

B. equal to par value.

C. more than par.