<span>1. Primero yo _voy_ al comedor. (a) 2. ____Como_________ pollo y una ensalada. (e) 3. ____Bebo_____ una Coca (b) 4. Le __doy ____ la llave a mi madre. (i) 5. ____Leo___ un libro fenomenal. (d) 6. __Deshago ____ las maletas. (f) 7. ___Pongo _____ la ropa en el armario. (c) 8. ____Uso_______ la computadora. (j) 9. ___Escribo_________ un e-mail. (g) 10. ____Duermo_________ en la cama. (h) </span>
Scientists think that algae first evolved approximately 2.7 billion years ago, and soon after this oxygen began to exist in the atmosphere. Photosynthesis by primitive plants and algae released oxygen, which gradually built up in the atmosphere.
