【题目】It was warm and nice that evening. I stayed awake until eleven in order to have a good look at the moon by myself.
A. on average B. on purpose
C. on business D. on time
在线课程【答案】B
【解析】考查介词短语。A. on average平均；B. on purpose故意地，特地；C. on business出差；D. on time按时，准时。句意：那天晚上天气又暖和又好。我特地坚持到十一点不睡觉就是为了好好地看月亮。表示目的，故选B。