Hearing their grandpa was ing, they began to the work to prepare for a nice dinner.
A. set off
B. set down
C. set aside
D. set about
网友回答
A. set off
B. set down
(答案→)C. set aside
D. set about
解析：set off 出发，动身；使爆炸。Set down写下；看做..。Set aside 留出，把...放在一边，不顾；驳回，撤销。 Set about 着手 ，开始做...根据句意：听说他们的外公快要来了，他们开始放下工作去准备一个丰盛的晚餐。可知选择C。