question: The differential analyzer by H.L. Hazen and Vannevar Bush was first being built in what year ?
answer: 1927
turker_answer: The differential anaylyzer by H.L. Hazen and Vannevar Bush was first built in 1927 .
rule-based: The differential analyzer by H.L. Hazen and Vannevar Bush was first being built in 1927 .