Rules for Sufficient Indicators: Unless, Without, Until

There are 2 steps for the SUFFICIENT Indicators (Unless, Without & Until). Step 1 states: Unless indicates a necessary condition, so the part that follows "unless" will be the necessary condition. Step 2: Negate the other part of the sentence and make it the sufficient condition. The example sentences show the sufficient part of the sentences include the word "cannot" which signifies a negation. However, in the 1st part of the answers you did not negate the sufficient conditions, which means the contrapositives are incorrect. Did I miss something? Please advise.