问题补充：
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
答案：
A. is sent
B. has been sent
(答案→)C. have been sent
D. are sent
解析：考查时态，根据题中的时间状语Up to now，应用现在完成时态，large quantities of+名词做主语时，谓语动词都用复数，故选C。
