1、reduce to “降低到……，减少到……”，介词to后面接的是最终的结果，也就是最后的位置或程度。
2、reduce by “降低了……，减少了“，介词by后面跟降低或减少的具体幅度。
拓展资料
reduce to
1、If this tool is used in development stage, we can reduce to resolution when issues are encountered in production.
如果在开发阶段使用这个工具，我们可以缩短解决生产环境中遇到的问题的处理时间。
2、Although there is a traditional view for how these processes work, it's not a requirement of the architecture for map and reduce to behave this way.
虽然这里存在一个这些过程如何工作的传统视图，但是它不是map和reduce体系结构所需要的。
3、This can sometimes cause predicates to reduce to the constant values true or false, allowing the entire location path to be simplified.
有时这可能使谓词减少到常量值true或false，允许简化整个位置路径。
4、The company must reduce costs to compete effectively.
公司要有效地参与竞争必须降低成本。
reduce by
1、We hope you can reduce by 1%.
我们希望你们能降低1%。
2、To decimate means to reduce by one-tenth; it does not mean to slash.
To decimate的意思是减少十分之一，而不是大幅削减。
3、If we could stay as vigorous as we are at twelve, it would take about 700 years for half of us to die, and another 700 for the survivors to be reduce by half again.
如果我们能一直像12岁时那样精力充沛，那就需要700年我们中的一半才会死去，而剩下的要减少一半又得再过700年。
4、First among them is the pledge to reduce by half the proportion of people in the world living on an income of less than one dollar a day.
千年发展目标中的第一条，就是把世界上每天收入不足一美元的人口减少一半。