I don't remember the book yesterday.
A:where I put
B:where did I put
C:where will I put
D:where I will put
—Sorry, Mr. Clark. I won't do it again.
如图,反比例函数y=kx(x>0)的图象经过矩形OABC对角线的交点M,分别于AB、BC交于点D、E,若四边形ODBE的面积为9,则k的值为____