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Drill Sergeant Mendonça barked orders to the Signal Corps students like a mad dog. Today's training was (demanding) than yesterday's, pushing the will-be NCO’s to their limits. The Signal Corps students are sure they are the (smart) bunch in academic disciplines, but they also needed to excel in their physical training. Mendonça, (mean) as a rattlesnake, kept reminding them of the consequences of failing the fitness test.
The obstacle course was the (bad) of all the exercises. They climbed walls, slogged through mud, and crawled under barbed wire, sweating like pigs. By lunchtime, they were exhausted and (hungry) than wolves. Sergeant Mendonça, however, would not let us rest. "This is not a picnic, gentlemen!" he yelled. The NCO academy is not for the faint of heart in fact, but the students are determined to make it.
Resolução comentada
Graus do adjetivo em inglês: identificar a afirmação correta sobre cada forma.
Em 'mean as a rattlesnake' há comparação de igualdade, então a forma correta é 'as mean as'. Por isso E está correta. As demais formas propostas violam as regras de comparativo e superlativo.
Análise das alternativas
A) Errada: o superlativo de 'smart' (monossílabo) é 'the smartest'. B) Errada: 'bad' tem superlativo irregular, 'the worst'; 'worse' é o comparativo. C) Errada: 'than yesterday's' pede comparativo, 'more demanding', e não 'most demanding'. D) Errada: 'hungry' faz o comparativo 'hungrier'; 'hungryer' não existe.
Referência: Gramática da língua inglesa: comparativos e superlativos.
Resolução comentada do VaiConcursos.