Research findings have shown that about 20 percent of people only 10 percent can be ____(分类) as “early birds”.
下列动物行为中,均属于先天性行为的一组是( )
已知函数f(x)=1+x-x22+x33-x44+...+x20132013,设F(x)=f(x+4),且函数F(x)的零点均在区间a,b(a<b,a,b∈Z)内,圆x2+y2=b-a的面积的最小值是 ( )