问题
                    
Often, when he something that him, he wasted his time dozing.
                            A:should be doing, gave
B:should have been doing, was given
C:should do, was given
D:should have been doing, had given
                        
                        B:should have been doing, was given
C:should do, was given
D:should have been doing, had given
正确答案是:
                        