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We're nearing the peak of the 11-year solar cycle, so double-check your GPS and watch where you're going.

On Thursday, the sun suddenly gave off a massive solar flare. Solar flares can disrupt(使中斷) radio communications, including devices that use Global Positioning System technology, such as cell phones, airplanes and car navigation（導航） systems.

So if you're relying on your GPS for driving directions, to find your location on your phone's mapping tool or for any other purpose, have a backup navigation system handy, such as a printed map. Even more importantly, pay close attention to where you are and where you're going. Don't rely solely on your GPS to give you directions.

In 2006, research from Cornell University proved that solar flares can cause GPS devices to lose signal. This can cause these devices to temporarily misrepresent your location or otherwise malfunction. "If you're driving to the beach using your car’s navigation system, you'll be OK. If you're on a commercial airplane in zero visibility weather, maybe not," said the researchers and they warned that after 2011 there would probably be lots of GPS disruptions.

In addition, solar flares can disrupt power systems. This week, National Geographic reported: "Under the right conditions, solar storms can create extra electrical currents in Earth's magnetosphere -- the region around the planet controlled by our magnetic(磁的) field. The electrical power grid（電網(wǎng)） is particularly likely to be affected by these extra currents, which can go into high-voltage transmission lines, causing transformers to overheat and possibly burn out." Across the nation, electric services and grid operators are preparing to respond to such problems.

A number of such blasts are expected over the next three to five years -- and the biggest flares are yet to come. This week's flare registered M9.3, about the highest level in the medium category. Larger flares that fall into the "X" category can cause global radio blackouts, but large M-class flares also can cause radio disruptions.

This is one of a series of recent chain reactions of severe space weather, as the solar cycle approaches solar maximum in 2013. Other major flares came in February and June, and more may follow. Remember to keep those printed maps handy.

72. ________ can help you better if massive solar flares break out.

　　　 A. The phone’s mapping tool.

　　　 B. Global Positioning System.

　　　 C. Car navigation systems.

　　　 D. The printed map at hand.

73. The underlined word “malfunction” refers to ________.

　　　 A. operate smoothly.

　　　 B. fail to run properly

　 C. crash as directed

　　　 D. manage appropriately

74. How many major flares have broken out according to the passage?

　　　 A. Once　　　　　　　

　　　 B. Twice　　　

　　　 C. Three times　　　　　　

　　　 D. Four times

75. Which will probably be the most suitable title?

A. Recent solar flare may disrupt your GPS

　　　 B. 2013, the solar cycle approaches maximum

　　　 C. Cornell University’s research on the solar flare

　　　 D. Never rely on your GPS for directions any longer