Can someone explain to me why these answers are incorrect? then explain the correct the answer?

Question 3. ¿Qué es un requisito para entrar el pre-kinder?

Answer 3: acta de nacimiento.

Explanation 3: Pre-kinder is a classroom-based preschool program for children below the age of five. To enter pre-kinder, it is necessary to prove age with a birth certificate.

Question 8: ¿Cómo puede producir menos contaminación del aire?

Answer 8: conduce menos.

Translation 8: How can you produce less air pollution? drive less.

Explanation 8: Motor vehicles pollute the air, and driving less reduces air pollution.

Question 12: ¿Qué NO es un saludo para una carta a la familia?

Answer 12: cordialmente

Translation 12: What is NOT a greeting for a letter to the family? Cordially

Explanation 12: cordially, it is used in business letters as a expression of courtesy and does not imply an expression of affection like the other expressions.  

tienen tantos camisas como nosotros.

explanation:

2 examples of how people live in their space and time defined with their particular characteristics