Answer:
1) Los residentes de nuestra ciudad enferman por la contaminación del aire.
2) El año pasado mas de cinco mil personas llegaron a nuestra ciudad.
3) Cada año hay más carros en las calles.
4) El problema de la contaminación va de mal en peor.
5) Los estudiantes de la universidad trabajan propuestas para solucionar este problema.
Step-by-step 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 present simple because is that the most apply by the sense of the sentence.
2. In the second sentence, was used the verb "llegaron" in preterite.
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.