Answer
elena es guapa
las muchachas son guapas
juan es guapo
juan y paco son guapos
elena y susana son guapas
nosotros somos guapos
No lavarse la boca y comer mucho dulce
The correct demonstrative adjective for this sentences would be "este".
* Este niño en la foto es mi primo Francisco". Because "ESTE" refers to a singular male subject. If it would have been a girl, the correct option would have been "ESTA". For plurals we need to use "estos" and "esa" when it is a singular, female and we point the subject at a certain distance. "Esa es mi prima" --> That is my cousin (over there)
Son las 7:30
Son las 8:00
Son las 12:40
Son las 3:15
Son las 5:15
Son las 6:20
Son las 9:05
Son las 9:45
Son las 10:00
You only use "es la" when it's 1:00 because is singular, you use "son las" when is plural im pretty sure :PP
