sure 是确定的意思，而absolutely则是绝对是的意思，区别可以从以下例子看出：
I am not sure he would be able to catch up with you, but I absolutely stay with you until you reach your destination. 我不确定他能不能赶上你，但我绝对会陪着你，直到你到达目的地。
水利万物而不争,
而万物莫能与之争。
