A subject pronoun replaces the name of a person or thing: I, you, he, she, it, we, they. Use a or an before a singular countable noun. Choose a/an by the first sound of the following word, not simply its first letter.
See it in action
Linh is my friend. She is a student.
She replaces Linh.It is a book.
A before the consonant sound /b/.It is an English book.
An before the vowel sound in English.Your turn: write two sentences using this pattern. Say them aloud and change one word to create a new sentence.