All About Comment Clauses in English

A comment clause, commonly heard in everyday speech and used in dialogue to  give it a natural tone, is a short word group, such as you see and I think, that adds a parenthetical remark to another word group. Its also called a  comment tag, a commenting tag or a parenthesis. You might not have known the name of it, but its guaranteed you use and hear it just about every day. Examples and Observations of a Comment Clause Commonly occurring examples [of comment clauses] are Im sure, Im afraid, I admit, I gather, I dare say and you see, you know, mind you, you must admit. Many comment clauses are stereotyped fillers which are inserted into running speech in order to establish informal contact with the hearer. When the subject is realized by I, their function is to inform the hearer of the speakers degree of certainty (I know/I suppose) or of her emotional attitude to the content of the matrix clause. -Carl Bache, Essentials of Mastering English (2000)As you know, the concept of the suction pump is centuries old. Really thats all this is except that instead of sucking water, Im sucking life. -Christopher Guest as Count Rugen in The Princess Bride (1987)The presentation went quite well, I believe.All time is all time. It does not change. It does not lend itself to warnings or explanations. It simply is. Take it moment by moment, and you will find that we are all, as Ive said before, bugs in amber. -Kurt Vonnegut, Slaughterhouse-Five  (1969)They [comment clauses] are so called because they do not so much add to the information in a sentence as comment on its truth, the manner of saying it or the attitude of the speaker. -Gunther Kaltenbock, Spoken Parenthetical Clauses in English: A Taxonomy (2007)Fly high above the cloudsOn the wings of a dreamI hear your whisper loud—Or so it seems. -Jackie Lomax, Or So It Seems Signals in Conversation The comment clauses you know and you see require some kind of response from the listeners, which, in a narrative turn, are more likely to be paralinguistic than vocal. Nods of the head, direct eye contact and minimal vocalizations like mm will satisfy the speaker that he still has the audiences consent to continue dominating the turn-taking. -Sara Thorne, Mastering Advanced English Language (2008) Comment Clauses and Relative Clauses In an example like Margaret Thatcher is now a life Baroness, which everyone knows, we can replace which with as with virtually no change of meaning. But unlike which, as is not generally used as a relative but as a conjunction. Note also that as everyone knows is positionally less restricted than which everyone knows: It could also be placed initially or medially. We, therefore, do not classify such an as-clause as a sentential relative clause but as a comment clause. -C. Bache and N. Davidsen-Nielsen, Mastering English  (1997)