I have got a loaf of bread; now I'm looking for a knife____. [ ]

A. to cut it with                    

B. to cut with it

C. with it to cut                    

D. it to cut with

一般监控系统使用的光端机采用（）光接口，为圆头，卡口；用于传输网络信号的光收发器采用光接口，为方头，卡口。