题干
What is happening in Japan made people all over the world _____________ sad.
A：feel
B：to feel
C： felt
D：feeling
答案(点此获取答案解析）
A
What is happening in Japan made people all over the world _____________ sad.
A：feel
B：to feel
C： felt
D：feeling
+y2=1交于P1，P2两点，线段P1P2的中点为P，设直线m的斜率为k1(k1≠0),直线OP的斜率为k2 ,则k1k2的值为…( )