Green can communicate safety to proceed, as in traffic lights. Green and red were standardized as the colors of international railroad signals in the 19th century. The first traffic light, using green and red gas lamps, was erected in 1868 in front of the Houses of Parliament in London. It exploded the following year, injuring the policeman who operated it. In 1912, the first modern electric traffic lights were put up in Salt Lake City, Utah. Red was chosen largely because of its high visibility, and its association with danger, while green was chosen largely because it could not be mistaken for red. Today green lights universally signal that a system is turned on and working as it should. In many video games, green signifies both health and completed objectives, opposite red.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Who was injured by a traffic light in Salt Lake City?
Ah, so.. unanswerable

After the Estonian War of Independence in 1919, the Estonian language became the state language of the newly independent country. In 1945, 97.3% of Estonia considered itself ethnic Estonian and spoke the language.
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Several dozen radioisotopes have been characterized. 65Zn, which has a half-life of 243.66 days, is the most long-lived radioisotope, followed by 72Zn with a half-life of 46.5 hours. Zinc has 10 nuclear isomers. 69mZn has the longest half-life, 13.76 h. The superscript m indicates a metastable isotope. The nucleus of a metastable isotope is in an excited state and will return to the ground state by emitting a photon in the form of a gamma ray. 61Zn has three excited states and 73Zn has two. The isotopes 65Zn, 71Zn, 77Zn and 78Zn each have only one excited state.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): How many nuclear isomers does zinc avoid?
Ah, so..
unanswerable