你们为什么不同意呢?
因为四个月的时间不够!工作肯定做不完!
In my opinion, if we delete“时间”,this sentence will be 因为四个月不够,工作肯定做不完。if I were the boss ,I will be anger and reply:“ 四个月不够,难道要五个月、六个月或者七个月吗?” but add“ 时间”,I will consider the time of the work, maybe its really short for the work?
the reason? I can't explain, just feel it.