Answer 1 El concierto de jazz es a las ocho de la noche.
Explanation 1: Time (SER)
The jazz concert is at eight o'clock at night.
Answer 2 Inés y Pancho están preocupados porque el examen va a ser difícil.
Explanation 2: Emotional state (ESTAR)
Inés and Pancho are worried because the test will be difficult.
Answer 3 La playa está sucia porque hay muchos turistas.
Explanation 3: Physical state or condition (ESTAR)
The beach is dirty because there are many tourists.
Answer 4 No puedo salir a tomar el sol porque está nublado.
Explanation 4: Weather expression (ESTAR)
I can not go out to sunbathe because it's cloudy.
Answer 5 En el verano, Tito es empleado del hotel Brisas de Loíza.
Explanation 5: Profession or occupation (SER)
In the summer, Tito is an employee of the Brisas de Loíza hotel.
Answer 6 Rita no puede venir al trabajo hoy porque está enferma.
Explanation 6: Health (ESTAR)
Rita can not go to work today because she is sick.
Answer 7 La motocicleta nueva es de David.
Explanation 7: Possession (SER)
The new motorcycle is owned by David.
Answer 8 (Yo) Estoy estudiando en la biblioteca porque tengo un examen mañana.
Explanation 8: Ongoing action (ESTAR)
I'm studying in the library because I have an exam tomorrow.
Answer 9 La piscina del hotel es grande y bonita.
Explanation 9: Characteristics (SER)
The hotel pool is large and pretty
Answer 10 Es importante estudiar, pero también tienes que descansar.
Explanation 10: Generalization (SER)
It is important to study, but you also have to rest.