From gramma book , "an" should be use before words with first letter with vowels (aeiou) , e.g. an egg , an umbrella .
But I just read "a university student" , "a duck egg" . It confuse me . What is the rule for use of "a" and "an" for words such as "university student / university uniform / duck egg / eagle egg / vanilla ice-cream" . Thanks for your help in advance .
Dear Raymott ,
Thanks for your instruction . I am Chinese . I don't know the meaning of vowels sound in the past , expect aeiou . Now I get some idea . Thank you .
It's affected by the word that follows it:
A vanilla ice-cream
And if you add an adjective that starts with a vowel sound, you do the opposite and change a to an:
An excellent book