The first reason is their size. They are very small and are very difficult to see. Special technology needed to be developed in order to observe them and their behavior and reach the conclusion that they were in fact infectious agents that could cause diseases. This wasn't possible before because the microscopes weren't as well developed.
Another is that they have a very long incubation period. This means that if you have them, a long time will pass before they start harming you which meant that many people believed them to be harmless since they couldn't track their behavior over a longer time period, also due to the lack of good technology.
For this one the answer is A because he was the one that trained the continental army during the winter at Valley Forge
Answer: C) Established permanent American military bases in Europe.
Explanation:
The First World War began in 1914, and the United States joined the war three years late after Germany had breached its neutrality treaty with America. The influence of the United States entering the war was significant. The additional firepower, resources, and U.S. troops helped to balance the war in favour of the Allies. To this end, they also organized several military bases throughout Europe, thus assisting the Allies.
Leonardo da Vinci <em>was famous for his designs, art, cartography, geology, and studies. Leonardo's designs later helped us to invent things like the tank, parachute, helicopter and many other things. He was also a very talented artist. Most of his pictures and paintings are in art galleries and museums. One of his most known paintings is the Mona Lisa. He made many maps of many different places. He was also interested in geology. He studied many different things, including math, reading, and writing backwards. People think he wrote backwards because he didn't want to smear the ink, but others thought he didn't want people to steal his ideas. </em>