"của tôi" ? Why not "của mình" ?
Can cái be used instead of chiếc?
I'm guessing there is a language rule about using thứ and chiếc?
Not that I know of, the person who did this module was apparently a Northerner. He/she enforced 'chiếc ví' too, even though there are plenty of 'cái ví's strewn around other modules in the course.
Could toi mua cai may tinh thu muoi cua minh be correct?