根据题意得：2m-1=m+1，
解得：m=2．
故答案为：2．
（）某类污染因子释放的某种污染物占该种污染物总量的百分数。
We’ll have to finish the job, _________.
A．long it takes however
B．it takes however long
C．long however it takes
D．however long it takes
