正常情况下，人体进食后不久，血液内（     ）

    Mr. Black was over fifty years old. He sometimes made some mistakes in his work, and he lost his work. So he had1time every day to do something. Then he often met his old friends under a big tree. They had drinks there and2anything they liked.

    One day, some old men were sitting together again and talking about young people in this world. They all agreed that the old people were3than young people. Then one of the old4said that young men were stronger than old men.

    5of them agreed that this was true,6Mr. Black didn't. He said, “No. I am as strong now as when I was a young man.” His friends were surprised7what he said.

    “Well,” said Mr. Black, “Near my house there is a big stone. When I was a young man, I used8to move it, but I couldn't because I was not9. I am an old man now, and when I try to move it, I still10. So, I am as strong as when I was young.”

在学校实验室开放时．同学们对手摇发电机非常感兴趣，他们想：发电机产生感应电流大小跟哪些因素有关呢？于是他们开展了探究，如图是他们所用的发电机和实验记录表：

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