Up to now, large quantities of food ____ to Africa to save the starving people.

A．is sent

B．has been sent

C．have been sent

D．are sent

08-32捣固车捣固作业时，ZF的传动路线被切断，柴油机的动力通过双向变量柱塞泵，驱动闭式回路的定量柱塞马达，通过（液压马达）减速箱和万向传动轴、ZF的输出轴，将动力分别传至前转向架的两根车轴。