问题

Is there a bridge over the river – Yes, there is ______ bridge over it.
A:a 800-metres-long
B:an 800-metres-long
C:a 800-metre-long
D:an 800-metre-long;
B:an 800-metres-long
C:a 800-metre-long
D:an 800-metre-long;
正确答案是: