1. Right answer:
an infinitive verb
After the construction acabar de must come an infinitive verb, but what is an infinitive verb? In Spanish, an infinitive verb is the most basic form of verbs, so verbs in the infinitive form are not conjugated. On the other hand, we can't know anything about who is performing an action or the tense at which this action is taking place. For instance, if we use the verb llamar, the phrase would be:
Acabar de llamar
2. Right answer:
acaba
Acaba is the conjugation of the verb acabar that matches the third person singular (here we use ella - she) in the simple present. The simple present tense is used to talk about habitual actions or routines. This tense is also used to describe things that happen now or in the near future. Finally:
Ella acaba
3.A. Right answer:
Voy comprar comida
This sentence has three words. First, the word voy is the conjugation of the irregular verb ir (to go) that matches the first person singular in the simple present. This person is yo (I) and hasn't been included here because in Spanish it is common no to include the subject pronoun in a sentence if the context is clear. On the other hand, the verb comprar (to buy) is given in infinitive form. Finally, comida is a noun that translates into food
3.B. Right answer:
Mi mamá va al zoológico
This sentence stands for the third person singular in the simple present. This is because mi mamá can be replaced by the subject pronoun for the third person singular in feminine form, which is ella. On the other hand, zoológico means zoo. Finally, this translates into:
My mom goes to the zoo
4. Right answer:
al
A contraction are short forms of a word or even a group of words made by leaving out a sound or letter. We use the contraction al when the preposition a comes before the definite article el. Therefore, the formula a + el = al. For instance, we can use this as follows:
Voy al parque (I'm going to the park)