The Sutong Highway Bridge a bridge is open to traffic.A. 320 metre longB. 320-metre-long

问题补充：

The Sutong Highway Bridge, a bridge, is open to traffic.

A. 320 metre long

B. 320-metre-long

C. 320 metres long

D. 320-metres-long

答案：

A. 320 metre long

(答案→)B. 320-metre-long

C. 320 metres long

D. 320-metres-long

解析：在英文中修饰名词表示量，可用连字符将单词连在一起，不使用复数，故本题选B。