Answer:
1) Los residentes de nuestra ciudad <u>enferman</u> por la contaminación del aire.
2) El año pasado mas de cinco mil personas <u>llegaron</u> a nuestra ciudad.
3) Cada año <u>hay</u> más carros en las calles.
4) El problema de la contaminación <u>va</u> de mal en peor.
5) Los estudiantes de la universidad <u>trabajan</u> propuestas para <u>solucionar</u> este problema.
Explanation:
In the text, there are some reasons to select the correct word for the blank:
1. In the first sentence was used the verb "enfermar" in <em>present simple </em>because is that the most apply by the sense of the sentence.
2. In the second sentence, was used the verb "llegaron" in <em>preterite</em>.
3. In the third sentence, was used the verb "haber" in its form "hay".
4. In the fourth sentence, was used the verb "ir" in its form "va".
5. In the fifth were used two verbs, the verb "trabajar" conjugated with the noun "nosotros" and the verb "solucionar" without modification.
All the text is allocated to environmental contamination.
