4.The river through our city,which is about _________,is clean again.

问题描述:

4.The river through our city,which is about _________,is clean again.
A.6000 metres long B.6000-metres-long
C.6000-metre-long D.6000 metre long
该选哪个?

没问题,肯定是A了.两种形式:6000 meters long或者6000-meter long.