题目

52. The two American came to China for a visit. They visited many places ______ and enjoyed themselves. A. interesting                B. interested                 C. of interest                 D. of interests 答案：C如图，已知双曲线y=（k＞0）经过直角三角形OAB斜边OB的中点D，与直角边AB相交于点C．若△OBC的面积为3，则k=    ．