1.No puedo ir contigo porque tengo que estudiar
2.A mi hermano menor no le gusta estar solo en la casa
3.El hombre espera el tren
4.Sólo tengo quince minutos para ayudarte
5.Mi amigo se llama Diego.Él es inteligente,atlético y cómico
6.¿Por qué estás corriendo en la casa?
Answer: Question 1 is A. C is wrong because without much notice would be informal. B is wrong because posting it on the newspaper it would be visible to everyone even people you don't know.
Question 2 The answer would be B because Madrid is the largest city in Spain. Answer A and C is wrong because both of them are true.
Question 3 the answer is B. Sorry I can't give an explanation I have to go. Let me know if these answers are correct.
Explanation: