题目

She fell over and blood from a cut on her head.（流出） 答案：【1】flowed已知f(x)在[a，b]上递增，g(x)在[a，b]上递减，设F(x)=f(x)+g(x)，G(x)=f(x)·g(x)．有下列四个命题：①f(a)+g(b)＜F(x)＜f(b)+g(a)                    ②f(a)+g(b)≤F(x)≤f(b)+g(a)③f(a)·g(b)＜G(x)＜f(b)·g(a)                     ④f(a)·g(b)≤G(x)≤f(b)·g(a)其中错误的有(    )A．1个                B．2个              C．3个               D．4个