bserve os pares de sentenças (X) e (Y). Assinale a opção correta. X Y The students walked to school. The children have walked to school. The cat meowed. The cat has meowed. He was sick. He had been sick. A Sentences in X are in the *simple past*. Sentences in Y are in the *past participle*. B Sentences in Y are in the *present perfect* ou *past perfect*. The auxiliary to have is inflected for tense and works together with the past participle to form verb phrases that indicate time (past) and aspect (completion). C Sentences in X are in the *simple past*. Sentences in Y are in the *past perfect*. D Sentences in X are in the past tense. Irregular verbs in the past indicate time (past) and aspect (completion). E Sentences in Y are in the *past perfect*. The auxiliary to have is inflected for tense and works together with the past participle to form verb phrases that indicate time (past) and aspect (completion).