一.interest当利息用时 ,为不可数 如： I borrowed the money at 5% interest.二.interest当兴趣用时既有可数名词又是不可数名词，看具体表示什么意思，例如下面的几种用法：1. 兴趣;关注;爱好I developed an interest in the machine.我对这机器发生了兴趣。
I have lost my interest in chemistry.我对化学已不感兴趣。
2. 趣味性(+to)Local color added interest to the novel.地方色彩增加了这部小说的吸引力。
3. 感兴趣的事物或人（这是就可数）His two great interests in life are music and painting. 三.股份,股权(+in)]He has an interest in the company.他在这家公司拥有股份四. 利润，福利，利益，好处 He always puts the interests of the people before his own. 他总是把人民的利益置于个人利益之上希望能帮到你，祝更上一层楼O(∩_∩)O。