In this task, you're given a context, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both context and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the context or linked information.

[Q]: Context: As the flotilla carrying the casket closed on Dover Castle Link Information: Built in the early 2nd century Answer: the early 2nd century
[A]: When was the building the Unknown Warrior's body was taken to built?


[Q]: Context: When Harry Truman became president in April 1945, upon FDR's death, the vice presidency Link Information: As such Truman selected Alben Barkley of Kentucky as his running mate in the 1948 presidential election. When Democrats regained control as a result of the 1948 elections, Answer: 8
[A]: How many years was Harry Truman president?


[Q]: Context: William the Conqueror, duke of Normandy, on the Norman invasion of England Link Information: William I (c. 1028 – 9 September 1087), usually known as William the Conqueror and sometimes William the Bastard, was the first Norman King of England, reigning from 1066 until his death in 1087. Answer: 0
[A]:
How long had the duke of Normandy held that title when he commenced invading England?