A rubric is a solid group of criteria for a student's assignment that has details on grades based on pre established criteria. If your teacher didn't create a rubric yet, the first thing is to politely ask for one. Begging to change your grade makes no sense if there's no strict criteria for it and talking to the principal should be the last thing to be done.
Every sentence has a verb. Some writers add onto the sentence in order to show that the activity continues over a long period of time or occurs in relationship to other events.
