3、n是一对孪生姐妹。an用在以元音音素开头的名词前,如anegg。即使单词拼写以辅音字母开头,如果单词的读音是以元音音素开头,也要用an,如anhour。反之即使单词拼写以元音字母开头但读音是以辅音音素开头,加不定冠词时也要用a,如auniversity。(1)常见的以元音音素开头的重点名词和形容词animal answer arm appleeasyeggeraserelephanteyehourideaimpoliteimportantinterestingorangeumbrellauncleu