How to use A/An The difference between A and An. A and An have the same Meaning. A and An are indefinite articles. The difference depends on the sound at the beginning of the next word. When the next word starts with a When the next word starts with a CONSTANT SOUND VOWEL SOUND a book a frog an apple an orange a car a lemon an egg a dog a truck an insect an umbrella an actor BE CAREFUL! The SOUND of the Letter is Important. Numbers Number 11 12 13 14 15 16 17 18 19 20 21 30 Cardinal Eleven Twelve Thirteen Fourteen Fifteen Sixteen Seventeen Eighteen Nineteen Twenty Twentyone Thirty 40 50 60 70 80 90 100 500 1,000 Forty Fifty Sixty Seventy Eighty Ninety One hundred Five hundred One thousand One thousand five hundred 1,500 Fifteen hundred One hundred 100,000 thousand 1,000,000 One million Personal Pronouns Personal Verb to Pronouns be I You He She It They We You am are is is is are are are Negative Possesive adjectives I am not You are not He is not She is not It is not They are not We are not You are not My Your His Her Its Their Our Your Structure of a sentence - Affirmative mode. Pronoun I She We Verb Play Cleans Study Direct Object Tennis The House The Lesson Free time Vocabulary Watch tv Got to the cinema Play videogames Listen music Read Surf the internet Play an instrument Go Shopping Do sports Share with the family Go out with friends Study Verbs in English Verb Listen Play Pay Share Study Read Watch Go Run Swim Wait En español Escuchar Tocar Pagar Compartir Estudiar Leer Mirar Ir Correr Nadar Esperar Family Tree Father Mother Son Daughter Brother Sister Aunt Uncle Cousin Niece Nephew Grandfather Grandmother Grandson Granddaughter Great Grandson/ Great Granddaughter