closed circulatory system
The economic system of the US is called Capitalism.
The first underground transport system in the United States was the Manhattan Elevated Railway, which opened in 1868. However, the first true underground subway system was the Boston Subway, which began operations in 1897. This pioneering system laid the groundwork for future urban transit systems across the country.
US system, or imperial system.
We need nutrients and oxygen to be supplied to our cells at a very fast rate as our cells need a lot of energy to keep us alive. Therefore we must have an efficient transport system to transport nutrients and oxygen to the billions of cells in our body. The transport system in man is known as the circulatory system.
the adversarial system
it is called: Free Enterprise
aliens toook a crapp an that's whut came out !
check my answer
Aerate, fertilize soil and as decomposers.
A mixed economy
The Imperial System.
It was called "Segregation" in US