The united states has a federal system of government. what does that mean? the national government has most of the power. the national government and states share power. local governments have most of the power. the national government is controlled by a small group of people.

Federal is a system of government. This means both the central government and the local government share power. Not sure if the sentences were questions, but I will answer them by numerical order.
1. Unitary
2. Federal
3. Confederation
4. Oligarchy (This is a type of government!)
Hope this helped!

It is meant that like tapestry scientific theories often need to pull out since they are not relevant and often times the whole chain of theories may be pulled out.