在任何情况下，（）必须单独以年费率为基础开价承保。

A.安装工程项目

B.建筑用施工机器、装置以及设备

C.工地内现成的建筑物

D.业主提供的物料及项目

Beijing is ranked first in terms of traffic jams and expenses for culture ________ Guangzhou is more open to peasant workers than Beijing and Shanghai.

A．when

B．since

C．while

D．because