问题
                    
Mr Green felt surprised and wondered _______.
                            A:when did she come back home
B:who did the cleaning this morning
C:how could I get to the post office
D:why they finish the work so early;
                        
                        B:who did the cleaning this morning
C:how could I get to the post office
D:why they finish the work so early;
正确答案是:
                        