Problem: Given the question: Extract the answer to the question from the following context. Question: What was one reason that the rollback policy for unification did not work out Context: The war started badly for the US and UN. North Korean forces struck massively in the summer of 1950 and nearly drove the outnumbered US and ROK defenders into the sea. However the United Nations intervened, naming Douglas MacArthur commander of its forces, and UN-US-ROK forces held a perimeter around Pusan, gaining time for reinforcement. MacArthur, in a bold but risky move, ordered an amphibious invasion well behind the front lines at Inchon, cutting off and routing the North Koreans and quickly crossing the 38th Parallel into North Korea. As UN forces continued to advance toward the Yalu River on the border with Communist China, the Chinese crossed the Yalu River in October and launched a series of surprise attacks that sent the UN forces reeling back across the 38th Parallel. Truman originally wanted a Rollback strategy to unify Korea; after the Chinese successes he settled for a Containment policy to split the country. MacArthur argued for rollback but was fired by President Harry Truman after disputes over the conduct of the war. Peace negotiations dragged on for two years until President Dwight D. Eisenhower threatened China with nuclear weapons; an armistice was quickly reached with the two Koreas remaining divided at the 38th parallel. North and South Korea are still today in a state of war, having never signed a peace treaty, and American forces remain stationed in South Korea as part of American foreign policy.
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The answer is:
Chinese crossed the Yalu River in October and launched a series of surprise attacks

Problem: Given the question: Extract the answer to the question from the following context. Question: Which parities are in opposition? Context: Legislative power lies with the Nitijela. The upper house of Parliament, called the Council of Iroij, is an advisory body comprising twelve tribal chiefs. The executive branch consists of the President and the Presidential Cabinet, which consists of ten ministers appointed by the President with the approval of the Nitijela. The twenty-four electoral districts into which the country is divided correspond to the inhabited islands and atolls. There are currently four political parties in the Marshall Islands: Aelon Kein Ad (AKA), United People's Party (UPP), Kien Eo Am (KEA) and United Democratic Party (UDP). Rule is shared by the AKA and the UDP. The following senators are in the legislative body:
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The answer is:
United People's Party (UPP), Kien Eo Am (KEA)

Problem: Given the question: Extract the answer to the question from the following context. Question: How are the earlier guns classified? Context: The US ended World War I with two 3-inch AA guns and improvements were developed throughout the inter-war period. However, in 1924 work started on a new 105 mm static mounting AA gun, but only a few were produced by the mid-1930s because by this time work had started on the 90 mm AA gun, with mobile carriages and static mountings able to engage air, sea and ground targets. The M1 version was approved in 1940. During the 1920s there was some work on a 4.7-inch which lapsed, but revived in 1937, leading to a new gun in 1944.
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The answer is:
mm