由题意：x>m+3;x<3m-1则当3m-1<=m+3时无解即m<=2
标准答案来了x-m-3>0,x>m+3x-3m+1<0,x<3m-1因为无解，说明m+3>3m-1-2m>-42m<4m<2答案，m<2
