One by one, the Classic cities in the southern lowlands were abandoned, and by A.D. 900, Maya civilization in that region had collapsed. The reason for this mysterious decline is unknown, though scholars have developed several competing theories. which is Maya had exhausted the environment around them to the point that it could no longer sustain a very large population. <span>Other Maya scholars argue that constant warfare among competing city-states led the complicated military, family (by marriage) and trade alliances between them to break down, along with the traditional system of dynastic power. As the stature of the holy lords diminished, their complex traditions of rituals and ceremonies dissolved into chaos. Finally, some catastrophic environmental change–like an extremely long, intense period of drought–may have wiped out the Classic Maya civilization. Drought would have hit cities like Tikal–where rainwater was necessary for drinking as well as for crop irrigation–especially hard</span>
Martin Luther main religious teachings was christainity.
The correct answer to fill up the blank is Merrimack.
In April 1854, the United States Congress authorized the construction of six similar warships, all named with river names. Created in 1855 and set up in Boston in December of the same year, the Merrimack was built in oak, it had the lines of a sailboat and was maneuvered easily even when it received only the thrust of the sails. The main weapon system was composed of Dahlgren cannons, a total of 40 fire hydrants. By the end of 1860, after five years of service, the Merrimack was towed into the naval arsenal of Norfolk, Virginia, due to some problems, and was still there when, on April 17, 1861, the state of Virginia separated from the Union. Three days later, the Union Navy abandoned the arsenal, burning, among others, seven important warships. Merrimack was one of them.
