Use a disfluent question or a proper question and find the answer to the question based on the given context or return None if an answer can't be found. A disfluent question is a question that has some interruptions in it while framing. A proper question is the correct form of the question without any disfluency.

Ex Input:
proper question: What river separates the Rhine from Duisburg?
disfluent question: What water oops actually river separates the Rhine from Duisburg?
context: Until the early 1980s, industry was a major source of water pollution. Although many plants and factories can be found along the Rhine up into Switzerland, it is along the Lower Rhine that the bulk of them are concentrated, as the river passes the major cities of Cologne, Dusseldorf and Duisburg. Duisburg is the home of Europe's largest inland port and functions as a hub to the sea ports of Rotterdam, Antwerp and Amsterdam. The Ruhr, which joins the Rhine in Duisburg, is nowadays a clean river, thanks to a combination of stricter environmental controls, a transition from heavy industry to light industry and cleanup measures, such as the reforestation of Slag and brownfields. The Ruhr currently provides the region with drinking water. It contributes 70 m3/s (2,500 cu ft/s) to the Rhine. Other rivers in the Ruhr Area, above all, the Emscher, still carry a considerable degree of pollution.

Ex Output:
None

Ex Input:
proper question: What non-Japanese empire did the Yuan dynasty succeed?
disfluent question: Which non-Chinese or no make that non-Japanese empire did the Yuan dynasty succeed?
context: The Yuan dynasty is considered both a successor to the Mongol Empire and an imperial Chinese dynasty. It was the khanate ruled by the successors of Mongke Khan after the division of the Mongol Empire. In official Chinese histories, the Yuan dynasty bore the Mandate of Heaven, following the Song dynasty and preceding the Ming dynasty. The dynasty was established by Kublai Khan, yet he placed his grandfather Genghis Khan on the imperial records as the official founder of the dynasty as Taizu.[b] In the Proclamation of the Dynastic Name (), Kublai announced the name of the new dynasty as Great Yuan and claimed the succession of former Chinese dynasties from the Three Sovereigns and Five Emperors to the Tang dynasty.

Ex Output:
None

Ex Input:
proper question: What Egyptian president jailed hundreds of members of the Brotherhood?
disfluent question: When was er what Egyptian president jailed hundreds of members of the Brotherhood?
context: Some elements of the Brotherhood, though perhaps against orders, did engage in violence against the government, and its founder Al-Banna was assassinated in 1949 in retaliation for the assassination of Egypt's premier Mahmud Fami Naqrashi three months earlier. The Brotherhood has suffered periodic repression in Egypt and has been banned several times, in 1948 and several years later following confrontations with Egyptian president Gamal Abdul Nasser, who jailed thousands of members for several years.

Ex Output:
None