问题补充：
--- will win the first place in the relay race?
--- I don’t know.
A. Do you think who
B. Do you think which class
C. Which class do you think
D. Whom do you think
答案：
A. Do you think who
B. Do you think which class
(答案→)C. Which class do you think
D. Whom do you think
解析：考察插入语用法。在英语中，插入语是一个很重要的用法，本句中的do you think作为插入语，不能放在句首，要放在句中。排除AB项，D项中应该使用who做主语。句意：你认为哪个班级在接力赛中能赢得第一名？—我不知道。
