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 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 devel 如图，在直角梯形ABCD中，AD∥BC，∠C＝90°，且AB＞AD＋BC，AB是⊙O的直径，则直线CD与⊙O的位置关系是 [　　] A． 相离 B． 相切 C． 相交 D． 无法确定