“Gentlemen, start your engines!” These famous words start races like the Indianapolis 500 and Daytona 500 where the best drivers race the fastest cars. But racing isn’t limited to professional racers who drive almost 200 miles per hour. Adults and children interested in the adrenaline rush of motorsports racing can drive a go-kart. In fact, many professional racers got their start driving go-karts. Racing go-karts, or karting, has become popular worldwide. In the past 50 years, an estimated 1.6 billion people worldwide have enjoyed some form of karting.
start your engines：（= get ready to do something）
adrenaline rush：（= doing something very enjoy）
In the late 1950s, Art Ingels built the first go-kart in California. Taking some metal tubes from his day job, building race cars, Ingels joined them together and added wheels and a small engine. People got excited about the kart and began building their own. The first karting championship race was held in 1964. Now there are competitive races held all over the world. Last April, 18 countries sent their best young racers to Austria to compete in the Red Bull Kart Fight World Final.
… be not limited to …（…不限於…）
Norma is as selfless as I am, Ron.
A man, a plan, a canal：Panama!