题目

Imagine it's 2035.You have a good job，a big family and you're about 40 years old.Welcome to your future life. Getting ready for work，you pause in front of the mirror.“Turn red，” you say.Your shirt changes from sky blue to deep red.Tiny preprogrammed electronics are rearranged in your shirt to change its color.Looking into the mirror，you find it hard to believe that you are 40.You look much younger.With amazing advances in medicine，people in your generation may live to be 150 years old.You're not even middle­aged. As you go into the kitchen and prepare to pour your breakf有理数在数轴上的位置如图所示，化简值是（   ）A．2m-nB．2m+nC．-2m-nD．n