It's :I am 15 years old........
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.
Explanation:
Answer: 1-Los chicos son simpáticos.
2- La ciudad es única
3- Los monumentos son antiguos
4- La plaza es agradable
5- El tráfico es horrible
Explanation: "La" is for singular
words that end with a. "Él" is for singular words that end with o. "Es" is for singular and "son" is for plural
