题目

31.The two ladies are _______ the same age, but there seems to be ten years _______ them. A. at; between     B. about; among      C. as; among       D. of; between 答案：D如图，四边形ABCD的对角线AC、BD相交于点O，且BD平分AC，若BD=8，AC=6，∠BOC=120°，则四边形ABCD的面积为       .（结果保留根号）