Is the following sentence acceptable?
As a student, my life revolves mainly around school.
There are teachers who would object to this on the grounds that the main clause is mis-related - after the opening 'As a student' you "should" (according to them) use 'I' as the subject of the main clause: you could say, for example, 'Being a student, I have a life that ...'. Alternatively you could use 'as a student' to qualify 'life': "My life as a student revolves..."
Not all teachers insist on this when there is no obstacle to understanding. I imagine most examination boards do though!