History was being divided into ERAs. What are they ?

PreCambrian, Palaeozoic, Mesozoic and Cenozoic

Explanation:

In the time scale above you can see that the Phanerozoic is divided into four eras: PreCambrain , Cenozoic, Mesozoic and Paleozoic. Very significant events in Earth's history are used to determine the boundaries of the eras. ... Subdivision of periods into epochs can be done only for the most recent portion of the geologic time scale.

s the president shall be commander in chief of the army and navy of the united states, and of the militia of the several states, when called into the actual service of the united states; he may require the opinion, in writing, of the principal officer in each of the executive departments. sooo yeahhh

explanation:

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