Your sentences don't work. These are the expressions used by native speakers: 1. He thought he knew everything. A "know-it-all" is a derogatory term. Nobody would "believe himself to be a know-it-all". 2. He is arrogant and sometimes behaves in a rather grotesque manner. "Grotesque" means shockingly inappropriate. We don't normally use "grotesque" to describe personality. "Ambiguous" means "unclear". Being arrogant and acting in a grotesque manner is not equivalent to "having an ambiguous personality"! "Arrogance" and "grotesque" can in no way constitute "a range". If you wish to use "to range" as a verb, the correct construction is "to range FROM A TO B". You can't use it here anyway because you don't have a range.

Hi, just a few points for you. (1) "He thought himself a know-it-all" or (2) "He believed oneself to be a know-it-all" I would say: (1) He thought of himself as a know-it-all (However, using the past tense of 'think' here 'thought', gives the impression that this man has changed his point of view since or has died- so maybe the present is better if he still thinks this. ie. He thinks of himself as a bit of a know-it-all.) Also this is slightly negative, and why would he think negative things about himself. Maybe he thinks of himself as shrewd, astute, clever, intelligent, smart, educated.. We think he's a know-it-all, he thinks he's Albert Einstein! (2) He believed himself to be a know-it-all. (This is far less common in my opinion) (3) "In terms of personality, he is very ambiguous. His personality range across the arrogance and the grotesque" This is more difficult as I am unsure what you mean by grotesque - weird, bizarre, rude, inappropriate, distasteful, horrible, disgusting. Maybe: In terms of personality, he is ambiguous, ranging from arrogance to the bizarre. Hope that helps a bit! Take it easy!

It would be "ranges across" not just "range" and if you were to use that you would take away "the" from "the grotesque". So: "His personality ranges across arrogant and grotesque" could work. "He believed himself to be a know-it-all" not oneself, oneself is used to talk about yourself. Know-it-all is usually mean, so he probably would not refer to himself in a way that was mean to him. "He thought he was a know it all" would work best, but as I said, being a know-it-all is not good. "He thought he was smart" would be better. Or, "people thought he was a know it all". sorry if this was no help!