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 如图所示的电路中,电源电压6V保持不变,定值电阻的阻值为10Ω,滑动变阻器的最大阻值为20Ω.当开关闭合,滑片由b端向a端移动的过程中,以下说法正确的是(  )

A:电压表的示数减小

B:电压表示数与电流表示数的比值不变

C:当滑片移动中点时,电压表示数为2V

D:当滑片移到a端时,电流表示数为0.2A

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B

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    Here's a selection of festivals for tourists to the United States in summer.

San Francisco Silent Film Festival

    Films at this odd cinematic event have a variety of musical accompaniments, including piano and violin. It includes some classic silent movies. If you want to see them all, you can buy a festival pass.

May 29 to June 1; www.silent film. org

Union Street Festival

    This popular street fair stretches out over six blocks of the city, in the fashionable shopping area of Union Street. This year, there's beer, wine tasting and more separate themes–––fashion, cuisine, tech, locals craft, and health and fitness.

    June 7 to 10: www.unionstreetfestival.com

North Beach Festival

    This is San Francisco's oldest street party, with live entertainment, delicious food and arts and crafts. Situated in the Little Italy district, known for its associations with the “Beat Generation”, festival goers are guaranteed plenty of good Italian food. There is also as the “blessing of the animals”, a San Francisco tradition which takes place at the National Shrine of Saint Francis of Assisi (610 Vallejo Street) at 2 pm on both days of the festival

June 14 to 16; www.sfhorthbeach. org

Stern Grove Festival

    This is the oldest free summer arts festival of its kind in the United States, It includes a wide variety of acts, from the local symphony orchestra to well-known artists such as Smokey Robinson.

Sundays from June 22 to Aug 24; www.sterngrove. org