Stop saying: “This is a my book.”
Say instead: “This is my book.” · A1 · Grammar
✗ Wrong
This is a my book.
✓ Correct
This is my book.
Why?
The words a and my do not go together. Use one of them, not both. Say: This is my book, or This is a book.
More examples
🎙️ REAL VOICES
The three correct examples below, in a real voice.
✗ That is a your pen.
✓ That is your pen.
✗ This is a his bag.
✓ This is his bag.
✗ She has a her phone.
✓ She has her phone.
A and my never meet — pick one.