(economics involves business and financial activities that show how people choose to use their limited resources (land, labor, and capital goods) to produce, exchange, and to consume goods and services)

(the laser that can produce quadrillions of pulses of light per second, creating a spot on a cell that is as hot as the sun)

(reversible English words that can be spelled forward and backward and still produce normal words with different meanings)

(using definitions and a letter added to the beginning of the second word of two words with the same spellings will produce two completely different words)