I agree with Anna and Grecious, but just think that more examples may help. 4.what is the difference between 盖 and 修建?( to build) This pair are synonyms in their meanings, but 修建 is written language while 盖 is colloquial. I will say 那里在盖一栋楼/建一栋楼 to my friend, but won't say 那里在修建一栋楼( because 修建 is too formal to use in everyday language) However, if you want to write in formal language, like in newspaper or in your assignment, I will suggest, 修建, for example: 市政府正在修建新工程, here if replacing 修建 with 盖, the sentence will sound colloquial. 5 what is the difference between 改变 and 换?( to change) 改变 and 换 sound similar, however they are definitely different. 改变 means change, 换 means exchange or replace. 我的家乡改变了很多. Here it is incorrect to say 我的家乡换了很多. 他用粮食换了很多衣服. Here it is incorrect to use 改变 too. Another thing for notice, the colloquial wording of 改变 is 变, e.g. 我的家乡变了很多. And the formal wording for 换 is 交换, e.g. 他用粮食交换了很多衣服. Hope that helps.

盖和修建，没有本质的区别，只是盖比较口语化。改变一般性格之类看不见的东西的改变。换没有具体的要求，个人见解，：）

4——what is the difference between 盖 and 修建?( to build) 盖 more oral, and normally appoint to the building (higher than ground). 修建 more official, and can use for every field, as building, playground, swing pool etc. 5_what is the difference between 改变 and 换?( to change) 改变 to be different as before, normal mentioned changes of one thing/person. 换 exchange, emphasize "ex", use one thing to replace another one.