∵f(x)在区间[a,b]上单调递减，∴f(b)-f(a)＜0又∵f(x)为奇函数，∴f(-x)=-f(x)∴f(-a)-f(-b)=-f(a)+f(b)＜0∴奇函数f(x)在区间[-b,-a]单调递减
