---- ?
---- Maybe the possible solutions to the air pollution.
A. Do you think what they are talking about
B. Do you think what are they talking about
C. What do you think they are talking aobut
D. What do you think are they talking about
网友回答
A. Do you think what they are talking about
B. Do you think what are they talking about
(答案→)C. What do you think they are talking aobut
D. What do you think are they talking about
解析： do you think可以看做是插入语，要放在疑问词What后面，且What引导的从句要用陈述语序，所以选C。