要使$\frac{\sqrt{x}}{\left|x\right|-5}$有意义，则字母应满足的条件是（　　　）

0也是自然数，自然数都是整数．

若四次测量一本书的宽度记录为：12.38cm，12.36cm，12.38cm，12.34cm，则这本书宽度平均值是（　　）

    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.”