sum /sʌm/ I. n. 1.［u］总数，总和: That is the sum of our experience. 那就是我们的全部经验。 The sum of two and two is four. 二加二的和是四。 2.［c］金额: a good sum 一笔可观的金额 The sales amount to a sum of ten thousand yuan.销售总额达1万元  3.［c］算术题: be good at sums 算术很好；do a sum in one’s head 心算 4. 用于习语 in sum 总的说来：The meeting was, in sum, a disaster.总的说来，这会议是一场灾难。‖II. vi. (summed; summing) 共计：The people summed to one thousand. 人数达1千人。sum up 总结，概括：to sum up experience 总结经验；sum sb. up 看清某人的性格；对某人有所品评