Differences between at least, at least and unless: the first two are synonymous and mean limit, the third does not

In the first sentence, for example, three chapters represent the minimum limit required: studying more is possible, while studying less is not enough. Unless: the exceptionWith unless the situation changes completely. The most common construction is:unless + not + subjunctiveThe Accademia della Crusca in fact includes “unless” among the subordinating conjunctions that normally require the subjunctive. “Unless that” is not the shortened form of “unless.” However, if you can say “if not”, “unless” or “except that”, then it serves unless.