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Disadvantages of electric traction include high capital costs that may be uneconomic on lightly trafficked routes; a relative lack of flexibility since electric trains need electrified tracks or onboard supercapacitors and charging infrastructure at stations; and a vulnerability to power interruptions. Different regions may use different supply voltages and frequencies, complicating through service. The limited clearances available under catenaries may preclude efficient double-stack container service. The lethal voltages on contact wires and third rails are a safety hazard to track workers, passengers and trespassers. Overhead wires are safer than third rails, but they are often considered unsightly.

What is a safety hazard to track workers?
Answer: voltages on contact wires
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The various Germanic states in the west all had coinages that imitated existing Roman and Byzantine forms. Gold continued to be minted until the end of the 7th century, when it was replaced by silver coins. The basic Frankish silver coin was the denarius or denier, while the Anglo-Saxon version was called a penny. From these areas, the denier or penny spread throughout Europe during the centuries from 700 to 1000. Copper or bronze coins were not struck, nor were gold except in Southern Europe. No silver coins denominated in multiple units were minted.

What was the Anglo-Saxon silver coin called?
Answer: penny
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20th Street starts at Avenue C, and 21st and 22nd Streets begin at First Avenue. They all end at Eleventh Avenue. Travel on the last block of the 20th, 21st and 22nd Streets, between Tenth and Eleventh Avenues, is in the opposite direction than it is on the rest of the respective street. 20th Street is very wide from the Avenue C to First Avenue.

At which Avenue do 21st and 22nd Streets begin?
Answer:
First