The verb to change in English is broad in its use. Chinese has more specific words.
改 -- To change [modify or correct]
改變 -- To change [modify]
變 -- To change [to become ...]
變成 -- To change in to [transformational]
換 -- To change [replacement], exchange
修 -- To fix [something broken]
你的數學作業完全不對！叫哥哥幫你改。
[Your math homework is completely wrong! Get your brother to help you].
中國女人結婚的時候改不改名字？
[Do Chinese women change their name after marrying?].
美國要中國改人民幣的匯率。
[The United States wants China to change the Yuan's exchange rate].
公司給員工免費的菜，後來有的人變胖了。
[Some people became fat when the company started giving its workers free food].
我要換工作，也許變成工程師。
[I want to change jobs and maybe become an engineer].
為了讓青蛙變成王子，公主需要吻它。
[In order to turn the frog in to a prince, the princess needs to give it a kiss].
去外面玩以前，應該先換衣服。
[You ought to change your clothes before going outside to play].
中國銀行可以給你換外幣拿人民幣。
[The Bank of China will exchange foreign currency for Chinese Yuan].
換一個說法。。。
[To say it another way, ...].
我不知道怎麼修自行車的輪胎。
[I don't know how to fix a bicycle tire].
政府准許你改名字。小偷常常換他的身分。
[The government will let you change your name. A thief often changes his identify].
上海改變了很多。
[Shanghai has changed a lot].
我改變我的想法了。
[I don't think about it the same anymore].
你要改一改你的壞習慣。
[You have to fix your bad habits].
他的問題變成我的問題了。
[His problem is now my problem].
