These photographs indicate the people of China and the people of ancient Peru modified their environment 1) create effective trade routes
2) increase the amount of land available for agriculture
3) move large quantities of water into cities
4) provide an effective defense

(2) increase the amount of land available for agriculture

the berlin blockade was an international crisis that arose from an attempt by the soviet union, in 1948–49, to force the western allied powers (the united states, the united kingdom, and france) to abandon their post-world war ii jurisdictions in west berlin. in march 1948 the allied powers decided to unite their different occupation zones of germany into a single economic unit. in protest, the soviet representative withdrew from the allied control council. coincident with the introduction of a new deutsche mark in west berlin (as throughout west germany), which the soviets regarded as a violation of agreements with the allies, the soviet occupation forces in eastern germany began a blockade of all rail, road, and water communications between berlin and the west. on june 24 the soviets announced that the four-power administration of berlin had ceased and that the allies no longer had any rights there.

the hollywood film industry of 1950 was threatened on several different fronts. television broadcasting was rapidly becoming the dominant entertainment medium in the united states. the paramount anti-trust consent decree requiring separate ownership for production companies and theater chains had gone into effect on 1 january 1950. large numbers of young men and women were marrying, having children, and moving to the suburbs, which affected the viability of downtown first-run movie theaters. foreign revenues were endangered by protectionist tactics including quota systems, high taxes, and blocked funds. finally, the morality and patriotism of hollywood films and filmmakers were under attack from government, religious, and citizens' groups.

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