I don't think it's good to drive eight hours without a rest.I agree .Eight hours ( ) really a very long time.A has B is C are D have 选一个

I don't think it's good to drive eight hours without a rest.
I agree .Eight hours ( ) really a very long time.
A has B is C are D have 选一个

B is
Eight hours 属于时间作主语,是单数.

B
英语中，表示度、量、衡等单位名词作主语时，即使是复数形式，也应该看成是一个整体，谓语动词通常用单数形式。