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During the development of a tree, the lower limbs often die, but may remain attached for a time, sometimes years. Subsequent layers of growth of the attaching stem are no longer intimately joined with the dead limb, but are grown around it. Hence, dead branches produce knots which are not attached, and likely to drop out after the tree has been sawn into boards.
A detached knot will probably drop out of the wood when someone saws it into what?
A: boards

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Everton were founder members of the Premier League in 1992, but struggled to find the right manager. Howard Kendall had returned in 1990 but could not repeat his previous success, while his successor, Mike Walker, was statistically the least successful Everton manager to date. When former Everton player Joe Royle took over in 1994 the club's form started to improve; his first game in charge was a 2–0 victory over derby rivals Liverpool. Royle dragged Everton clear of relegation, leading the club to the FA Cup for the fifth time in its history, defeating Manchester United 1–0 in the final.
In what year was Mike Walker made Everton manager?
A: unanswerable

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The primacy of the composer's written score has also led, today, to a relatively minor role played by improvisation in classical music, in sharp contrast to the practice of musicians who lived during the baroque, classical and romantic era. Improvisation in classical music performance was common during both the Baroque and early romantic eras, yet lessened strongly during the second half of the 19th and in the 20th centuries. During the classical era, Mozart and Beethoven often improvised the cadenzas to their piano concertos (and thereby encouraged others to do so), but they also provided written cadenzas for use by other soloists. In opera, the practice of singing strictly by the score, i.e. come scritto, was famously propagated by soprano Maria Callas, who called this practice 'straitjacketing' and implied that it allows the intention of the composer to be understood better, especially during studying the music for the first time.
What is the name for the practice of singing strictly by the score in opera?
A: come scritto

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The slide rule was invented around 1620–1630, shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions. Aviation is one of the few fields where slide rules are still in widespread use, particularly for solving time–distance problems in light aircraft. To save space and for ease of reading, these are typically circular devices rather than the classic linear slide rule shape. A popular example is the E6B.
When was the slide rule first invented?
A:
1620–1630