1.improve on意为 “比……好，改进；做出比…更好的成绩”，也可用作improve upon；

The second edition greatly improves on the first edition.

第二版比第一版好得多。

We can only improve on the situation, right?

我们只能改善现有情况，对不？

He's never improved on his first book.

他从未写出比他第一部著作更好的书。

We need to improve on our performance against France.我们需要比对阵法国队时表现得更好。

We've certainly improved on last year's figures.

我们的业绩的确超过了去年的数字。

Whatever is offered by the bank is unlikely to be improved on by any rival suitor.

其他竞争收购方不大可能开出比这家银行更高的价码。

Improve： I improved my car.

Improve on: I improved on my car.

第一句，我改善了我的车，那我可能通过替换、改装它部分零件来实现完善它 （by replacing some of the parts）.

第二句，可能改善的方法便是重新买一辆新的、更好的、或是升级版的车，来更新我自己的车

2.improve in意为“改进”

侧重于 整体的改善，一般不用于针对细节的提升，比如提升英语是一个大方面的，可以用improve in；

I try to improve in reading exercise.

我尝试通过练习提升阅读能力。

She improved in English.她的英有进步。

You can improve your English by reading more.

你可以通过多阅读来提升你的英语水平。(“ by”来表示“通过什么手段”)

He is certainly improving in his spelling.

它的拼写确实改进了很多。

He has much improved in health.

他的健康状况大有改善。

Her health has improved in leaps and bounds.

她的健康已迅速好转。

There is little doubt, however, that things will improve in the not too distant future.

不过事情在不久的将来会有所改善，这几乎毋庸置疑。

It has changed who we are and continues to fuel our optimism about how much the lives of the poorest people will improve in the years ahead ．

它改变了我们的身份,并继续激励我们对未来几年最贫困人群生活的改善保持乐观态度。高考真题- 2016 四川