当这些参数变量发生变化时，函数曲线随之变化，从而直观的显示出曲线的动态变化，反映出各参数和函数曲线的关系，加深对多种函数曲线的理解。

" Maybe because in the era of the working class teen, you could get a job at a video store and still afford a car and drive around with your friends and feel free. The sense I had, my friends had, ...