He was wandering in the park, ________ his time watching the children playing.
A.savingB.killingC.sparingD.costing在线课程B
解析：
从was wandering…可知，他在“消磨、打发时间”。kill one's time常译为“消磨、打发（时间）”。A，C，D三项都不具有此意。