Câu 49 - 50 Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions. 49. The artist died of a long-term mental illness. The well-kept secrets about his life were revealed later. A. Not until the well-kept secrets about the artist's life were revealed did he die of a long-term mental illness. ADIEUONTHLORO B. Only after the artist died of a long-term mental illness were the well-kept secrets about his life revealed. C. Had the artist died of a long-term mental illness, the well-kept secrets about his life wouldn't have been revealed. D. Hardly the well-kept secrets about the artist's life were revealed when he died of a long-term mental illness. 50. Humans weren't conscious of wildlife preservation. A large number of species went extinct. A. If a large number of species had gone extinct, humans would have been conscious of wildlife preservation. B. If humans had been conscious of wildlife preservation, a large number of species wouldn't have gone extinct. C. If humans hadn't been conscious of wildlife preservation, a large number of species wouldn't have gone extinct. D. If a large number of species hadn't gone extinct, humans would have been conscious of wildlife preservation.