题目内容：
Accurate Timer (精确记时器)These days timing is everything．Between meetings and appointments, deadlines and conference calls, my schedule requires that I know the time down to the minute．Even on weekends, I have a football team to coach, shows to tape, and planes to catch．If I'm late, I'm sunk．The problem is that it's hard if my clocks aren't correct．Even the digital clocks can display time inaccurately．Dead batteries, time changes, "" any of these can cause a clock to be inaccurate．Now there is no need to worry, because advanced radio technology has produced a clock which gets the time directly from the U．S．Atomic Clock in Fort Collins, Colorado, the standard for time-keeping all over the world．The Atomic Clock by Acron is the most accurate, reliable and convenient timepiece you can have.
Every morning at 1:00 a.m, this "smart" clock in Colorado automatically resets itself to the exact hour, minute and second．The U．S．Atomic Clock is accurate to ten billionths of a second per day．This means that the clock deviates less than one second over a one-million-year period．The Atomic Clock even adjusts automatically for daylight saving time,so you don't have to remember to "spring forward" or "fall back"．The desktop clock model is the only atomic clock that will not lose time with low power or when you change its batteries.
The most accurate clock in the world is of no use if it is difficult to operate．The Acron Atomic Clock is engineered in Germany using the latest scientific technology．It comes in two styles, the wall clock and the desktop model．Both are designed to be functional and easy to use．The desk clock's display features the exact time (in hours, minutes and seconds) , month and date, or you can choose to display any two U．S．or world time zones．It weighs only eight ounces, and is the perfect travel clock．It also has dual alarms,perfect for couples．Both the desktop and the wall models have an internal antenna for good reception without unattractive wires.What is the passage mainly about? A．The importance of timin
B．The working principle of an ordinary cloc
C．The features of the Atomic Cloc
D．The manufacturer of the Atomic Cloc
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