Hello, I am a Spanish Speaker and would like to help you. So, we use the subjunctive to express <em>desires, doubts, the unknown, the abstract, and emotions</em>. As in the indicative, the subjunctive mood includes the same verb tenses, including the perfect, the past, and the future. So we can affirm three characteristics regarding the subjunctive:
a) Subjunctive sentences often have one subject in the main (independent) clause and one in the noun (dependent) clause. For instance: Yo quiero que tú laves los platos <em>(I want you to do the dishes).</em>
b) Subjunctive sentences often have parts linked by a relative pronoun (que, quien, como). For instance: Yo quiero que tú laves los platos <em>(I want you to do the dishes).
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c) Subjunctive sentences often contain a WEIRDO verb, that is, the acronym that stands for Wishes, Emotions, Impersonal Expressions, Recommendations, Doubt/Denial, and Ojalá. All these situations are likely to be used in the subjunctive. For instance: Yo quiero que tú laves los platos<em> (I want you to do the dishes).</em>
In this way, we can solve this problem as follows:
1. Es una lástima que los autos contaminen tanto.
Verb: Contaminar
Conjugation: Contaminen (Matching the third-person plural)
2. Me alegro de que tanta gente se interesen por la ecología.
Verb: Interesar
Conjugation: Interesen (Matching the third-person plural)
3. Es terrible que las naciones desarrolladas usen tantos recursos naturales.
Verb: Usar
Conjugation: Usen (Matching the third-person plural)
4. Espero que el gobierno use más programas para resolver el problema.
Verb: Usar
Conjugation: Use (Matching the third-person singular)
5. No me gusta que mis vecinos no reciclen las botellas y las latas.
Verb: Reciclar
Conjugation: Reciclen (Matching the third-person plural)
6. ¿Te sorprende que ellos recojan la basura sólo una vez a la semana
Verb: Recoger
Conjugation: Recojan (Matching the third-person plural)