Answer:
la causa principal es la quema de combustibles fósiles
Answer: These are the correct answers:
1. por
2. por
3. para
4. para
5. para
6. por
Explanation: Just to elaborate a little on the answer, it can also be added that in this exercise they are asking you to choose the most appropriate preposition. "Por" can be translated as by, among other meanings, and "para" can be translated as for, among other meanings as well. So, for instance, in sentence 6, the speaker is saying: "My cousin was raised BY my parents." And in sentence 3, the speaker is saying "I bought some flowers FOR Ana."
Carmen tiene que limpiar su dormitorio.
2. Teresa ( deber estudiar ) DEBE ESTUDIA
3. Yo ( assistir a clases) ASISTO A CLASES
4. Esteban (escribir cartas). ESCRIBE CARTAS
5. Tú ( leer libros). LEES UN LIBRO
6. Nancy ( vender libros). VENDE LIBROS
