题目内容：

Could you tell me---?A.when will they leave Beijing.B.when could they leave Beijing
C.when they will leave BeijingD.why she did't come to school

优质解答

应选C,宾语从句应该用陈述的语序（连词+主语+谓语）,而且这里的could表示委婉的语气,不表过去,他们还没有离开北京,所以应该用将来时态.