To pronounce 'vaccine', you start with a V sound, then the A as in 'cat', " vak" , a K sound, and then " seen" , as " I've seen you before" .

单词“'vaccine”的发音从一个 V 音开始，然后是“cat”中的 A 音，“vak”，接着是一个 K 音，然后是单词“see”的过去分词“seen”。