是指这个单词是元音音素开头的,注意不一定是元音字母开头,应该是指这个单词的读音是元音开头,如：orange,apple,egg.还有hour虽然是第一个字母是辅音字母h,但是h不发音,所以这个单词是元音开头的,所以前面也要加an,如...

　　这些我会，我想问哪些是元音音素。

　　20个元音音素对应元音音素例子：1)[i:]sea,he,see,piece,ceiling2)[i]sit,build,miss,myth3)[e]bed,desk,head,4)[ae]bad,land,bank,stamp(a和e中间是连起来的)5)[ɔ]hot,want6)[ɔ:]door,more,sport,ball,warm,author,court,bought,caught7)[u:]good,who,blue,soup,8)[u]look,put,women,could9)[a:]car,fast,class,plant,calm,aunt　10)[ʌ]cup,come,blood,rough　11)[ə:]girl,work,serve,nurse12)[ə]cadre,ago,forget,polite,dollar,doctor,famous,Saturday13)[ei]cake,they,play,eight,great,14)[ai]bike,die,neither,light,try,find,height,eye15)[əu]phone,cold,boat,soul,grow16)[au]house,town17)[ɔi]boy,oil18)[iə]dear,idea,deer,here,fierce,19)[ɛə]pear,care,there,fair20)[uə]tour,poor,