这个英文句子有没有问题

1. get this job 最好是用过去式 got
2. could gain，您的意思是“能赚”多少多少钱，比较地道的表达方法就是直接用动词earn或者是make,"...they earn/make more than..."
3. eight thousand yuan,这里的thousand是表示单位，用单数形式
4. 然后最后一“句”没有动词，不是完整句子。
干脆给您直接写出修改后的句子吧：
For instance, three of my classmates got this job, and now they make more than eight thousand yuan per month, which is much higher than the average income of my other classmates.

For instance, three of my classmates get this job and they can gain more than eight thousand yuan per month ,which is much higher than the average income of my classmats.

For instance, three of my classmates get this job,and they could gain more than eight thousands(去掉s) yuan per month.Much higher than the average income of my classmats(classmates)

没问题 除了classmats少了个e：classmates

get改成got更好一些