原式=-3-[-5+(-1×1/5)/(-2/5)]=-3-[-5+(-1/5)/(-2/5)]=-3-(-5+1/2)=-3+5-1/2=3/2如果我的回答能够帮到你,请点击【选为满意回答】--------------------予人玫瑰  手留余香------------------------------------...