下列运算结果正确的是 [ ]

A． 3m+2n=5mn            

B． 5m-3m=2 

C． 7m+m=8m²            

D． 3m²n-2nm²=m²n

Between the two parts of the concert is an interval,          the audience can buy ice – cream.

A．when

B．where

C．that

D．which