This is a key aspect of a unitary system of government -The national government can revoke only certain decisions made at lower levels of government.

- The national government controls all foreign and economic policy Certain powers are delegated to lower levels of government states , cities, etc. -and the national government has little or no authority in those areas.

- The national government has supreme power over lower levels of government , which carry out the policies of the national government .

The national government has supreme power over lower levels of government, which carry out the policies of the national government .

Explanation:

A unitary form of government is a form of government that gives all major powers to the central government. There is no power sharing among the local and national government rather all the policies and decisions are made by the national government.

A key aspect of a unitary system of government is that national government has supreme power over lower levels of government, which carry out the policies of the national government.

The local governments can implement and execute only those decisions and policies laid out by the national government. Counties like France, UK, Colombia, etc have a unitary system of government.

the two atomic bombs dropped on japan in 1945 killed and maimed hundreds of thousands of people, and their effects are still being felt today. the uranium bomb detonated over hiroshima on 6 august 1945 had an explosive yield equal to 15,000 tonnes of tnt.