一个数______是3的倍数，这个数就是3的倍数．
一个数各个数位上数的和是3的倍数，这个数就是3的倍数；
故答案为：各个数位上数的和．
Peter received a letter just now his grandma would come to see him.[ ]
A. saying
B. Said
C. to say
D. says
全球水循环的关键是( )。
A．海洋
B．大气
C．陆地
D．森林
