D is alright, coz, u might get a very high mark on another course to average that up. but with an F, u need to retake this course again, do all the assignment again, pay the money again, and at the end, u will get two mark for this course. If u got a C for example, average that up, it means u got D twice in this course ( i think that;s how they caculate it), so it will lower your cgpa a lot. So, if there are any course u really need to take, STUDY HARD, don;t get an F, it will affect a lot.