单选题 The course normally attracts 20 students per year, ______ up to half will be from overseas.
A. in which B. for whom C. with which D. of whom

【正确答案】 D

【答案解析】[解析] 由于该非限制性定语从句的前置词为students，所以只能用whom作关系代词。正确答案为D，up to half of whom表示“一半以上的学生”。例如：He has two brothers，one of whom is now a PLA man．他有两个哥哥，其中一位是解放军战士。