题干

如图3所示,一金属球原来不带电,现沿球的直径的延长线放置一均匀带电的细杆MN,金属球上感应电荷产生的电场在球内直径上a、b、c三点的场强大小分别为Ea、E­b、Ec,三者相比较( )

A:Ea最大

B:Eb最大

C:Ec最大

D:Ea=Eb=Ec

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C

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    Owning a smartphone may not be as smart as you think. It may let you surf the Internet, listen to music and snap photos wherever you are…but it also turns you into a workaholic, it seems.

    A study suggests that, by giving you access to emails at all times, the all-singing, all-dancing mobile phone adds as much as two hours to your working day. Researchers found that Britons work an additional 460 hours a year on average as they are able to respond to emails on their mobiles.

    The study by technology retailer Pixmania reveals the average UK working day is between 9 and 10 hours, but a further two hours is spent responding to or sending work emails, or making work calls. More than 90 percent of office workers have email-enabled phones, with a third accessing them more than 20 times a day. Almost one in ten admits spending up to three hours outside their normal working day checking work emails. Some workers confess(承认) they are on call almost 24 hours a day, with nine out of ten saying they make work emails and calls outside their normal working hours. The average time for first checking emails is between 6 a.m. and 7 a.m., with more than a third checking their first emails in this period, and a quarter checking them between 11 p.m. and midnight.

    Ghadi Hobeika, marketing director of Pixmania, said, “The ability to access literally millions of apps, keep in contact via social networks and take photos and video as well as text and call has made smartphones invaluable for many people. However, there are drawbacks. Many companies expect their employees to be on call 24 hours a day, seven days a week, and smartphones mean that people literally cannot get away from work. The more constantly in contact we become , the more is expected of us in a work capacity(容量).”

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