问题补充:
--- Do you know ?
--- Next Sunday.
A. what they will do
B. what will they do
C. when will they come
D. when they will come
答案:
A. what they will do
B. what will they do
C. when will they come
(答案→)D. when they will come
解析:宾语从句。根据答语可知提问时间用特殊疑问词when;根据语序故选D。