问题补充：
Do you know Guangzhou tomorrow?
A. whether they leave for
B. whether will they leave for
C. whether they are leaving for
D. whether do they leave for
答案：
A. whether they leave for
B. whether will they leave for
(答案→)C. whether they are leaving for
D. whether do they leave for
解析：英语宾语从句中一般为陈述语序。其时态和主句没有必然联系。根据本句时间状语tomorrow，可知从句中描述的是将来发生的动作，故用一般将来时态。选项B为倒装语序。由于英语中leave等表示位移的动词的现在进行时态也可以表示将来发生的动作，故选C。
