若三球的半径之比是1：2：3，那么半径最大的球体积是其余两球体积和的（　　）倍．

A．4

B．3

C．2

D．1

According to the recent regulation, it is required that any chemical plant that_______ along the river _______ to build a recycling center for the waste.

A．locate; has

B．locates; have

C．is located; have

D．is located; has