instruction:
In this task, we ask you to write a question that asks about "event duration", based on a given sentence. The question will likely start with "How long". Your question should be answerable based on the common knowledge of how long certain events usually last. Don't create questions which have explicit mentions of answers in the text. Instead, it has to be implied from what is given. In other words, we want you to use "instinct" or "common sense". Note that the written questions are not required to have a single correct answer.
question:
Sentence: About 30% of Ratners's profit already is derived from the U.S.
answer:
How long did it take to make profit?


question:
Sentence: Durer rejected Alberti's concept of an objective beauty, proposing a relativist notion of beauty based on variety.
answer:
How long did it take Alberti to form his concept of objective beauty?


question:
Sentence: A thwarted Mongol invasion in 1274 weakened the Kamakura regime.
answer:

How long did the invasion last?


