1、不定冠詞有a(an)與數詞one同源,是一個的意思。a用於輔音音素前,一般讀作e,而an則用於元音音素前,一般讀做en。
2、表示一個,意為one;指某人或某物,意為acertain。AMr.Lingiswaitingforyou.
3、代表一類人或物。Aknifeisatoolforcuttingwith.Mr.Smithisanengineer.
4、詞組或成語。alittle/afew/alotof/atypeof/apile/agreatmany/manya/asarule/inahurry/inaminute/inaword/inashortwhile/afterawhile/haveacold/haveatry/keepaneyeon/allofasudden