题目

Mary and Donald Smith lived in the same building. Donald 41 a toy company. One day Donald gave Mary. the 4-year-old girl. a new toy. She played with it and said. This is fun! A few weeks later Donald gave her 42 toy. She played with it and then said. I'm not 43 in this toy. It doesn't work. For years Donald gave Mary new toys.  and she gave him very good   44   about the toys. When Mary was 13 years old. Donald showed her a new ball. Mary wanted to 45 the ball with small stones to make it 46 .The company made this change. Mary's idea was a great success! The company sold thousands 10．已知函数f（x）=x2-kx-2在区间（1，5）上既没有最大值也没有最小值，则实数k的取值范围是（　　）A．[10，+∞）B．（-∞，2]C．（-∞，2]∪[10，+∞）D．（-∞，1]∪[5，+∞）