单选题
The weekend program of special activities for handicapped children was a great success thanks to those who generously ______ their time.
【正确答案】
D
【答案解析】who generously ______ their, time是定语从句，修饰those，横线处应填入以their time为宾语的动词。本句时态为过去时，故选(D) volunteered。volunteer one's time表示“自愿花 时做某事”。