/ɪmˈpru:vmənt ||; ɪmˈpruvmənt/noun [C,U] (an) improvement (on/in sth) (a) change which makes the quality or condition of sb/sth better 改进；改善: Your written work is in need of some improvement. 你的笔头作业须要改进一下。 We use improvement in to talk about something that has got better than it was before There's been a considerable improvement in your mother's condition. Improvement on is used when we are comparing two things and one is better than the other These marks are an improvement on your previous ones. 说某事物比过去有改进，要用improvement in：There's been a considerable improvement in your mother's condition.你妈妈的情况好多了。比较两个事物，一个比另一个好，就要用improvement on：These marks are an improvement on your previous ones.你这次分数比上次高。