improve in 表示在某一方面有所改进或提高，improve on 表示在原有基础上进行改进或提高或做得比原来更好（其否定式意为已经够好了或无法再好了）。比较：
She improved in English. 她的英有进步。
He has improved in health. 他的健康状况已有好转。
He has never improved on his first book. 他再也没有写出比他的处女作更好的作品来。
比较下面两组句子：
He has improved her poem. 他已经修改了她的诗。
He has improved on her poem. 他写的一首诗比她的诗更好。
The poem cannot be improved. 这首诗没有什么可改的地方。
This poem cannot be improved on. 这首诗已经够好了，再也 写不出比这更好的了。
My tutor helps me to improve in my study.
我的家庭老师帮助我在学习上取得进步。
Please fill out this questionnaire so we can improve our service.
请填写这份调查问卷，这样就能帮助我们改善服务。
The teacher gave me lots of instruction to improve my English.
老师给了我很多指导来提高我的英语。
N-UNCOUNT. 瑜伽;瑜伽术. Yoga is a type of exercise in which you move your body into various positions in order to become more fit or flexible, to improve your breathing, and to relax your mind.
I want to improve myself in English.
我想提高自己的英语水平。
※Improve your time and your time will improve you. 珍惜时间，时间才会珍惜你。
※Never neglect an opportunity for improvement. 抓住大好时机，切莫等闲错过。
※To care for wisdom and truth and the improvement of the soul is far better than to seek money and honour and reputation. 获得智慧，寻求真理，并使心灵美好，要比追求金钱、荣誉和名声好得多。
