— Excuse me, could you tell me where the nearest post office is?

— The nearest post office? You will have to walk _____. [ ]

A. 500-metres away

B. 500 metre far

C. 500 metres farther

D. 500-metre-far away

The teacher speaks very loudly        all the students can hear her.

A．so that

B．because

C．since

D．when