Hello. I have a question about the word unless. According to a dictionary, in most cases, the word unless can be replaced with the expression if ... not, but in some cases not. The dictionary says that you can say "I'll be surprised if Ann doesn't come to the meeting," but that you cannot say "I'll be surprised unless Ann comes to the meeting." I was wondering how different the two expressions "unless" and "if ... not" are. I try making up the following sentences in which the two expressions are used. (A) He will be angry if you don't come to the meeting. (B) He will be angry unless you come to the meeting. I think that (A) and (B) have almost the same meaning. However, if I try to find differences between the two, I think in the case of (A), it mentions only the case that "you" don't come, but it does not mention the case "you" come. Therefore, there is still a possibility that "he" will be angry even if "you" come to the meeting, say, if you have very bad news. However, in the case of (B), "he" won't be angry only if "you" come to the meeting, which means there is no possibility at all that "he" will be angry if "you" come to the meeting, no matter whether you have bad news or not. Am I right? Or am I too concerned about logic? Maybe language used in ordinary life is not that strict in terms of logic. Thank you.