If this coutinues to take place at the present rate ,

问题描述:

If this coutinues to take place at the present rate ,
_____another fifty years ,the world will be crowded with big ants.
A at B for C in D on
请选择

For 长达...年
若你这样的速度发展50年 世界上将是蚂蚁的世界.