题目

Her sons, both of ______ work abroad, will come back home this summer. A. that                B. who             C. them                D. whom 答案：D如图，已知AD是△ABC的外接圆的直径，AD =13 cm，，则AC的长等于（    ） A．5 cm    　             B．6 cm     C．10 cm　 　             D．12 cm