问题
                    
About _______of the engineers in my company seem to be in their _________.
                            A:second-nines; fourties
B:two-ninths; forties
C:second-ninths; fortieth
D:two-nineths; fourtieth
                        
                        B:two-ninths; forties
C:second-ninths; fortieth
D:two-nineths; fourtieth
正确答案是: