"could still" "still could"孰先孰后?

问题描述:

"could still" "still could"孰先孰后?
搞不太清楚,语感上觉得应该这么说:
Most Chinese students,who are mostly grown ups,COULD STILL not have a good command of their money.
额……还有那个WHO我不知道用得对不对……这算是什么从句啊?我在大学学英语好像全凭了语感了,语法全忘了,好瘥啊

WHO用在这里是可以的
属于定语从句,定students的
could still not?
这里用的有点不通
可以把still去掉
意思都差不多一样……