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The roots of hard rock can be traced back to the 1950s, particularly electric blues, which laid the foundations for key elements such as a rough declamatory vocal style, heavy guitar riffs, string-bending blues-scale guitar solos, strong beat, thick riff-laden texture, and posturing performances. Electric blues guitarists began experimenting with hard rock elements such as driving rhythms, distorted guitar solos and power chords in the 1950s, evident in the work of Memphis blues guitarists such as Joe Hill Louis, Willie Johnson, and particularly Pat Hare, who captured a "grittier, nastier, more ferocious electric guitar sound" on records such as James Cotton's "Cotton Crop Blues" (1954). Other antecedents include Link Wray's instrumental "Rumble" in 1958, and the surf rock instrumentals of Dick Dale, such as "Let's Go Trippin'" (1961) and "Misirlou" (1962).
What type of music known as the roots of hard rock was started in the 1940s?
A: unanswerable

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While LEDs have the advantage over fluorescent lamps that they do not contain mercury, they may contain other hazardous metals such as lead and arsenic. Regarding the toxicity of LEDs when treated as waste, a study published in 2011 stated: "According to federal standards, LEDs are not hazardous except for low-intensity red LEDs, which leached Pb [lead] at levels exceeding regulatory limits (186 mg/L; regulatory limit: 5). However, according to California regulations, excessive levels of copper (up to 3892 mg/kg; limit: 2500), lead (up to 8103 mg/kg; limit: 1000), nickel (up to 4797 mg/kg; limit: 2000), or silver (up to 721 mg/kg; limit: 500) render all except low-intensity yellow LEDs hazardous."
According to a California study, what harmful metal is in most non-LEDs?
A: unanswerable

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The first part of the campaign went well, with John outmanoeuvring the forces under the command of Prince Louis and retaking the county of Anjou by the end of June. John besieged the castle of Roche-au-Moine, a key stronghold, forcing Louis to give battle against John's larger army. The local Angevin nobles refused to advance with the king; left at something of a disadvantage, John retreated back to La Rochelle. Shortly afterwards, Philip won the hard-fought battle of Bouvines in the north against Otto and John's other allies, bringing an end to John's hopes of retaking Normandy. A peace agreement was signed in which John returned Anjou to Philip and paid the French king compensation; the truce was intended to last for six years. John arrived back in England in October.
Who won the battle of Bouvines?
A: Philip

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Carnival Tuesday hosts the main events. Full costume is worn, complete with make-up and body paint/adornment. Usually "Mas Boots" that complement the costumes are worn. Each band has their costume presentation based on a particular theme, and contains various sections (some consisting of thousands of revelers) that reflect these themes. The street parade and band costume competition take place. The mas bands eventually converge on the Queen's Park Savannah to pass on "The Stage" for judging. The singer of the most played song is crowned Road March King or Queen earning prize money and usually a vehicle.
What is usually worn on the feet to compliment the costumes?
A:
"Mas Boots"