题目

He wrote the letter ________, though he didn't have enough time.A.carefully enough B.enough carefully C.enough careful D.careful enough 答案：【答案】A【解析】句意：他写这封信很仔细，尽管他没有足够的时间。考查enough用法。carefully认真地；careful认真的。根据wrote the letter可知，此处空格修饰动词wrote，故用副词carefully，而enough修饰副词时要后置，故选A。如图，AB为⊙O的直径，CD⊥AB于点E，交⊙O于点D，OF⊥AC于点F．（1）证明：△ABC∽△DBE；（2）若∠CAB=30°，AF=，用扇形OAC围成一个圆锥，求该圆锥底面圆的半径．