根据各组对话内容，从下面提供的5个选项中选出能填入空白处的最佳选项。

A:Could I use your dictionary, please

B:()

A:Thank you. I’ll return it as soon as possible.

A．Sure. What is it

B．It’s very nice of you to say so.

C．It’s nothing.

D．Have a nice trip!

E．Certainly, Here you are.

在切断或接通线路负荷电流或环路电流时，应尽量使用（）.

A、闸刀

B、自落熔丝

C、开关

D、杆刀