Answer:
In order to complete this exercise, you have to fill-in the blanks in the sentences using the correct form of the preterite or imperfect past form of the verbs provided in brackets as appropriate for each case.
<em>In general, the preterite will be used to describe completed actions in the past, while the imperfect is used to describe actions that occurred habitually in the past. </em>
<em>Note that in order to choose the correct inflection of each verb you have to pay special attention to the subject in each sentences.</em>
Explanation:
1. Marcos <em>estuvo</em> (estar) enfermo cuando regresó de sus vacaciones.
2. Dos enfermeras <em>entraron</em> (entrar) a la habitación esta mañana.
3. Todos los veranos nosotros <em>íbamos</em> (ir) a visitar a los abuelos.
4. Ayer, el doctor me <em>recetó</em> (recetar) unas pastillas.
5. De niño, ¿tú <em>te caías</em> (caerse) con frecuencia?
