【题目】He's going to take a holiday with friends once the exams are________ and he has exciting plans for the summer holidays.
A.at the end
B.by the end
C.in the end
D.at an end

【答案】D
【解析】句意：考试结束后，他计划和朋友度假放松，他还制定了令人兴奋的暑假计划。at an end固定短语，“结束”故选D。