What percent of garbage can be burned as fuel

In 1819, what did the united states obtain from spain for $5 million?

Which of these constitutional amendments made all people born or naturalized in the united states into citizens of the united states ?

Human beings spread all around the world over a period of millions of years. identify when humans arrived in different regions of the world. 200,000 years ago 100,000 years ago 40,000 years ago 30,000 years ago