Answer: The numeral 20
Explanation:
For the Maya, the basic unit of time, a day, was called a kin. In the second order, 20 kins made up a uinal. In a vigesimal system the third order would be 20 uinals but, instead, 18 uinals made up a tun. Thus a tun was 360 kin (days)
Answer: Ecological Succession {Succession}
Explanation: During succession the organisms within an ecosystem can change it's abiotic conditions.
Answer: <em>B. The ironclad
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Explanation:
The main battle between ironclads occurred on 9 March 1862, as the defensively covered Monitor was conveyed to shield the Union's wooden armada from the ironclad smash Virginia and Confederate warships. With the clash of Hampton Roads, maritime fighting changed forever. Ironclads were warships intended to be impenetrable to foe shot and shell by the excellence of their iron-shielded wooden structures.
Different names for these boats incorporate rams, defensive layer clads, iron gophers, iron elephants, iron pine boxes, turtle-backs, and mud-smashers. So incredible were the ironclads that they upset an ancient axiom of naval warfare that forts were stronger than ships.