不定冠詞有哪些 不定冠詞用法有哪些？

1、不定冠詞有a (an)與數詞one 同源，是一個的意思。a用於子音音素前，一般讀作e，而an則用於母音音素前，一般讀做en。

2、表示一個，意為one；指某人或某物，意為a certain。 A Mr. Ling is waiting for you. 　

3、代表一類人或物。 A knife is a tool for cutting with. Mr. Smith is an engineer. 　　

4、片語或成語。 a little / a few / a lot of / a type of / a pile / a great many / many a / as a rule / in a hurry / in a minute / in a word / in a short while / after a while / have a cold / have a try / keep an eye on / all of a sudden