a 放在辅音发音的单词前,表示一,如a book , a bag, a tescher a pupil
an放在元音发音的单词前,如, an apple, an English book, an hour, 也表示一
some 是一些的意思,是复数,有接可数名词复数如some books
some pupils, some friends, some apples, some pencils.等
a和an是冠词,后加可数名词的单数形式,其中a后加辅音开头的名词,an加元音开头的名词。比如,一个苹果是an apple.一本书是a book. some是不定代词,后面可以跟可数名词复数,也可以跟不可数名词。比如,一些书是some books.一些水是some water.