——It's reported that many people were hurt in Kunming Terrorist Attacks (恐怖事件)on March 1st.——_______ bad news!
A:What
B:How
C:What a
D:How a
如图,Rt△AOC的直角边OC在x轴上,∠ACO=90°,反比例函数y=kx经过另一条直角边AC的中点D,S△AOC=3,则k=( )