Answer:
1. vuelva
2. trabajemos
3. contaminar
4. vamos
5. terminó
6. observar
7. cambiemos
8. estén
9. sea
Explanation:
The exercise aims for you to choose between the subjunctive mode or to conjugate the verbs depending on the tense required by the sentence.
The subjunctive mode is a grammatical mode that encompasses different values, within which we find the statements that are uncertain or hypothetical, or desires. These are the cases of sentences 1, 2, 7 8 and 9, these examples give an idea of hypothetical situations.
The other sentences are conjugated in PRESENT, PAST or are in INFINITIVE form according to each sentences tense.
Here is the translation of the complete sentences:
1. I will study ecology when I return to university.
2. We cannot avoid climate change, unless we all work together.
3. We cannot drive without polluting the air.
4. We always collect a lot of trash when we go to the park.
5. Elisa spoke with the president of the Ecology Club after the meeting ended.
6. We go on an excursion to observe animals and plants.
7. Pollution will be a very serious problem until we change our production and transportation systems.
8. The government must create more national parks before forests and rivers are completely contaminated.
9. People recycle in order to doesn't be difficult.
