题目

下列计算正确的是（ ） A . 2a2+3a3＝5a5 B . a6÷a2＝a3 C . D . （a﹣3）﹣2＝a﹣5 答案：C— Have you got your result of the final? — Not yet. I was told that the papers _____. [     ]A. were still being graded B. were not gradingC. have already been gradedD. have not grading