VERBO TO BE PRESENTE SIMPLE v/s PASADO SIMPLE

PRESENTE SIMPLE EN PRESENTE EL VERBO [ TO BE ] SE ESCRIBE DE 3 FORMAS DIFERENTES, SEGÚN EL PRONOMBRE QUE USEMOS. I AM A DOCTOR YOU ARE MY FRIEND HE IS THE NEW STUDENT SHE IS SMART IT IS SMALL WE ARE FAMILY YOU ARE MY TEAM THEY ARE MY PARENTS EXPRESA SER O ESTAR : I SHE IS A DOCTOR / SHE IS HAPPY [ + ] I SHE IS NOT A DOCTOR / SHE IS NOT HAPPY [ - ] IS SHE ...