题目

In modern society there is a great deal of argument about competition. Some value it highly，believing that it is responsible for social progress and prosperity.Others say that competition is bad；that it sets one person against another；that it leads to unfriendly relationship between people. I have taught many children who held the belief that their self worth relied (依赖)on how well they performed at tennis and other skills.For them，playing well and winning are often life and death affairs. In their single minded pursuit(追求)of success, the development, of many other hu关于晨昏线的叙述，错误的是(    ) A．晨昏线是昼半球与夜半球的分界线   B．晨昏线任何时候都平分地球 C．晨昏线上的太阳高度为零   D．在夏至日，晨昏线与地轴在同一平面内且与太阳光垂直