Чем материальная точка отличается от геометрической?

This is my family.  My father is an engineer.  He works in a factory.  My mother is a doctor 
She works at a large hospital. She is at work now. My aunt is a teacher at school. The school is good.  My aunt isn't at school now. She is at home. My sister is at school. She is a schoolgirl. 
My sister has a big black cat. 

This is my family.
My father is an engineer 
He works in a factory.  
My  mother is a doctor 
She works at a large hospital.
She is at  work now.
My aunt is a teacher at a school.
The school is good.
My aunt is not at school now.
She is at home.
My sister is at school.
She is a schoolgirl.
My sister has a  big  black cat.