题目

如图，AB是⊙O的弦，C是AB的三等分点，连结OC并延长交⊙O于点D。 若OC=3，CD=2，则圆心O到弦AB的距离是(    )A.6 B.9- C.D.25-3 答案：CI have two brothers, ________of them is good at English.A.bothB.everyC.eitherD.and neither