c On the contrary, but rather (introducing a word or clause that contrasts with or contradicts the preceding clause or sentence without the not).
c however | However, although, nevertheless (implies that the following clause is contrary to prior belief or contrasts with or contradicts the preceding clause or sentence).
c except | Except that (introducing a subordinate clause which qualifies a negative statement); also, with omission of the subject of the subordinate clause, acting as a negative relative, "except one that", "except such that".
c Without it also being the case that; unless that (introducing a necessary concomitant).