My father was preparing for his speech __ my mother was doing some washing last night.

A．if

B．while

C．unless

D．until

持票人因不获承兑或不获付款，对其前手行使追索权时，对持票人承担连带责任的有（）。

A、出票人

B、付款人

C、背书人

D、保证人