I'm pretty sure some they are People adapt to their environment, changes to the earths enviroment can be benificial, Changes to the earth environment can be harmful, people change their environment, I'm sorry if I'm wrong on some of these. I hope this helps also :)
Until the early Proterozic there were only negligible amounts of free oxygen in the atmosphere
-- so that other scientists can reproduce your experiment in their labs
-- so that when you go back and read your own experiment next year,
you'll be able to remember and understand what you did
Answer:
Every river is part of a larger system—a watershed, which is the land drained by a river and its tributaries. Rivers are large natural streams of water flowing in channels and emptying into larger bodies of water.A tributary is a smaller stream or river that joins a larger or main river.
