Marking test

I'm wondering why some lecturers here tend to ask the GA to mark the test paper?
This is my second experience marking the test paper..because for me, it is a test!!!the lecturer know better how to mark it  whether to give good mark @not...
And the worst thing,tomorrow i need to submit the mark..
The lecturer does not tolerate with me even though I already mention to him I'm having presentation..
The test just conducted on last monday and tuesday..
I hope this semester will be the last sem i work with that lecturer,.,...
In positive thinking, I know the true colors of the lecturer...and maybe I will deal with this type of attitude in future...