Answer:
You could use one to see if that $210934879207344329 dollar "living" wood table is living or not. It could also be used at hospitals...
Sorry never heard of that "key" in my life...
The path electrons take to orbit the nucleus is called shell.
I'd say agriculture, though in more recent years you could argue for mining.
Asia. In certain regions the diagnosis is as high as 95% of the population.