一道英语题，请大家帮忙！

-What do you think of the report on the UFO? -Great! Many students were interested in it and they kept on standing ___A___ the end of the meeting A. until B. in C. on D. about

答案是A。题目意思是：---你觉得这场关于UFO的报告怎么样？---太棒了！许多学生非常感兴趣，他们一直站到会议结束。可以理解为与会人员太多了，有一部分不得不站着参加，但是他们太感兴趣了，以至于站到整个会议结束。