I have stated that "do" occurs in one/sixteenth of occurences, so clearly many people do utilize it. (Supply Google Ngram Viewer) But that disparity suggests to me that there may be a thing missing in it. I counsel that it is the vagueness of "do" which makes it unsatisfactory. http://pay-for-exams42962.widblog.com/49744870/rumored-buzz-on-pay-for-exams