题干

如图1所示是研究光电效应的电路.某同学利用该装置在不同实验条件下得到了三条光电流I与A、K两极之间的电极UAK的关系曲线(甲光、乙光、丙光),如图2所示.则下列说法正确的是(   )

A:甲光对应的光电子的最大初动能小于丙光对应的光电子的最大初动能

B:甲光和乙光的频率相同,且甲光的光强比乙光强

C:丙光的频率比甲、乙光的大,所以光子的能量较大,丙光照射到K极到电子从K极射出的时间间隔明显小于甲、乙光相应的时间间隔

D:用强度相同的甲、丙光照射该光电管,则单位时间内逸出的光电子数相等

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A,B

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    Mary Krupa became friends with the grey squirrels during her first week at Penn State,after spotting them running around and idly(漫不经地)wondering what they would look like with tiny hats on their heads.Today, everyone at the university knows her as the "Squirrel Girl".

    Mary started bringing them food,and gradually they began to trust her.She managed to put a hat on a squirrel and take a picture.Thinking that her colleagues could do with something to lift up their spirits,she started posting similar Photos on Facebook.The response Was greatly positive,and before long Mary and her squirrels became an Internet sensation.

    Growing up in a neighborhood outside State College,Mary was always fond of birds and animals around her home,but she didn't interact with people very much.She was later diagnosed with Asperger's syndrome,but the squirrels changed that.The squirrels are actually a good way to break the ice,because I'll be sitting here patting a squirrel and other people will come over and well just start like feeding the squirrels together and chatting about them,"she said."I am a lot more outgoing.

    And in case you're wondering how Mary is able to get the squirrels to do what she wants for her photos,it has a lot to do with food.For example,whenever she wants them to hold or play with something,she puts peanut butter on the prop(道具),and they'll grab it.But getting to that part took a while.In the beginning,she would throw peanuts up the trees on campus and invite the squirrels to come down and get them,but they hesitated to approach her.She had the patience to earn their trust,though.

    This year,Mary is graduating with a degree in English and wildlife sciences.She wants to be a science writer and educate people on how to preserve the environment.As for her furry friends,Mary plans to stay in the area and visit them as often as she can.