воткните артикль ,где нужно 1.My....son is....pupil. 2.You have....pen. Give me....pen. 3

1. My son is a pupil. We dont use articles after possessive pronouns. 

2.You have a pen. Give me the pen. In the first sentence we used an Indefinite article because the subject (pen) is not identified. In the second sentence we used the definite article because the subject is defined by the situation.

3 These are books. The books are good. In the first sentence we used an indefinite article because the subject (pen) is not identified. In the second sentence we used the definite article because the subject is defined by the situation.

4 Do you like ice-cream? We used no article because ice-cream here is used in the generic sense. Compare: Would you like an ice-cream? Here we use an indefinite article to denote any portion of ice-cream. 

5  The winter this year is very cold. We used the definite article because we speak about the winter which is clearly  defined:  the winter this year. There is only one winter every year.