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1. 然而，直到1963年，研究人员才首次研制出预防麻疹的疫苗。

   rán'ér, zhí​dào1963 nián, yán​jiū​rén​yuán cái shǒu​cì yán​zhì chū yù​fáng má​zhěn de yì​miáo.

   However, it was not until 1963 that researchers first developed a vaccine to prevent measles.

   Source: CCMatrix