For this case we have the following demonstrative adjectives:
1) This
2) Those
The translation of these adjectives in Spanish is different depending on whether the gender is male or female.
For the male gender we have:
This = Este
Those = Esos
For the female gender we have:
This = Esta
Those = Esas
Using these definitions, we can complete the sentences:
Esta selva es muy verde. (This).
Esos cerdos sons muy sucios. (Those).
Esas chicas son alumnas. (Those)