Answer:
Spread
Explanation:
People use envelopes very often. The germs people carry are put into the envelope and then it's sent out to many others.
Answer:
An increase in the combustion of fossil fuels
Explanation:
Competition allows science to advance at a faster pace.
Think of it as an arms race: when a country builds one battleship, their enemy builds two. This continues as both countries try to outdo each other. Competitive science works the same way.
They come from females when they make love to males.
