问题
                    
Could you please tell me — Two days ago.
                            A:when did you go for a picnic
B:when you went for a picnic
C:when will you go for a picnic
D:when you will go for a picnic;
                        
                        B:when you went for a picnic
C:when will you go for a picnic
D:when you will go for a picnic;
正确答案是:
                        