—If you eat ,you won't be too heavy.
A:happily
B:quietly
C:properly
D:politely
下列属于学习行为的是( )
如图,四边形OABC是矩形,四边形ADEF是正方形 ,点A、D在x轴的负半轴上,点C在y轴的正半轴上,点F在AB上,点B、E在反比例函数y=kx的图象上,正方形ADEF的面积为4,且BF=2AF,则k值为____ .