cumulative: implies a constant increase (as in amount or power) by successive addition, accretion, or repetition: the ~ effect of taking a drug for many months.  注意只有1个m     successive泛指连续，无论间隔长度      如scientific knowledge is cumulative科学知识是积累起来的       accretion增长增加，和create都来自词根CRE: to grow, to come into being


accumulative: may distinctively imply that something has reached its maximum or greatest magnitude through many additions: the ~ impact of a well-ordered sales presentation.       cumulus积云，在拉丁中表示一堆heap        又如the accumulative effects of pollution污染的累积效应，表示已经达到某种程度


additive: implies that something is capable of assimilation to or incorporation in something else OR of growth by additions: as new art forms arise, we develop an ~ notion of what art is.        additive information/samples可附加信息/可附加样本，如completely additive完全可附加性，即additional表示附加的，而additive表示"可"附加的，是两个词的区别


summative: implies that something is capable of association or combination with others so as to create a total effect: the ~ effect of the show's music, dancing, and staging.    没有找到summative其他例句，请参考本词例句


cumulative累积: 指逐渐持续增加增长，accumulative累积:  表示已经积累到最大程度，additive增加: 表示可以增加，无论方式，summative总体: 表示和其他因素联合结合，达到整体效果


记忆方法: 1）首字母CAAS首字母想成是ASAC尽快as soon as capable<==累积            这四个词都以后缀tive结尾，表示有某种倾向或作用，又如acquisitive贪婪的imaginative富有想象力的talkative爱说话的

         2）累积的意思是增加增长mean increasing or produced by the addition of new material of the same or similar kind.