在下图4×4的正方形网格中，△MNP绕某点旋转一定的角度，得到△M₁N₁P₁，则其旋转中心可能是（  ）

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    Do you want to cure all the diseases in the world? It seems like an impossible job, but Priscilla Chan is trying really hard to achieve it.
Chan is a 32-year-old woman from the United States. Many people may know her as the wife of Mark Zuckerberg, the founder of Facebook. But Chan herself has done a lot to help people.
    Chan and Zuckerberg said in September they would give out $3 billion(20 billion yuan) in the next 10 years to help deal with all of the world's diseases. As a doctor, Chan was a big driver in this decision. “We hope that all of our children can live long and healthy lives in the future,” she said.
    Besides health, Chan also cares about children's education. Before becoming a doctor, Chan taught science to fourth and fifth graders at a school in California for a year. This year she started a project called The Primary School. It provides education for children from kindergarten to the twelfth grade.
    Chan herself knows how important education is to a child. She has a Chinese father and a Vietnamese mother. Her parents didn't receive much education. But they worked hard to make sure Chan and their other two daughters would have the best opportunities. Chan went to Harvard University in 2003 and now works as a doctor. “ I realized that I was so lucky to be what I was,” said Chan. “so now, I will try my best to help others. I hope they can also have their opportunities to reach their dreams and be what they would like to be.”

下列电路中，电流表测L₁灯电流的是（   ）

为了鼓励小强做家务，小强每月的费用都是根据上月他的家务劳动时间所得奖励加上基本生活费从父母那里获取的．若设小强每月的家务劳动时间为 $x$ 小时，该月可得（即下月他可获得）的总费用为 $y$ 元，则 $y$ （元）和 $x$ （小时）之间的函数图像如图所示．

已知函数，若存在，使得不等式成立，则实数的最小
值是