我国古代有着辉煌的数学研究成果．《周髀算经》、《九章算术》、《海岛算经》、《孙子算经》、…、《辑古算经》等算经10部专著，有着十分丰富多彩的内容，是了解我国古代数学的重要文献．这10部专著中有7部产生于魏晋南北朝时期．某中学拟从这10部名著中选择2部作为“数学文化”校本课程学习内容，则所选2部名著中至少有一部是魏晋南北朝时期的名著的概率为（   ）

林木径级是指森林中原木的直径值，通常用cm来表示，下图为我国长白山北坡岳桦林种群林木径级随海拔动态变化图。据此完成下列各题。

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    Mr and Mrs Yates had one daughter.   1   name was Carol, and she was nineteen years old. Carol lived  2 her parents and worked in an office. She had some friends, but she  3any of the boys very much.

    Then she met a very  4 young man. His name was George. and he  5  in a bank near her office. They went out together quite  6 , and he came to Carol’s parents’ house twice, and then last week Carol went to her father and said, “I  7 George, Daddy. ”

    “Oh, yes,” said  8  .“he’s a nice boy. But has he got any money?”

    “Oh, men! All of you are  9  ,” the daughter answered    10  . “I met George on the first of June and on the second he said to me, ‘Has your father got any money?’”

下列说法不正确的是（   ）

关于《杜甫诗三首》，下列说法中不正确的一项是(    )