improve
1.下面五句都可以说：
- I hope your health will improve.
- I hope your health will be improved.
- I hope you will improve in health.
- I hope you will be improved in health.
- I hope you will improve your health.
第二句不及其他各句自然。第五句跟其他各句略有不同，含有“没法增进健康”的意思。
2.improve跟improve upon不同。如He has improved her poem是“他已经修改了她的诗”。He has improved upon her poem是“他已经作了比她的诗好的一首诗”。This poem cannot be improved是“这首诗好（或坏）得不能修改了”，This poem cannot be improved upon是“这首诗好得没有更好的了”。
3.He hoped to improve himself是“他希望在知识或学问上进步”。He hoped to better himself是“他希望在境遇或地位上进步”。
