如图，AB∥CD，CB平分∠ABD．若∠C=40°，则∠D的度数为（　　）               

A．90°                         B．100°                       C．110°                       D．120°

方程组的解是（　　）                                                             

A．                     B．                     C．                     D．

下列计算正确的是（　　）                                                                     

A．a²a³=a⁶                    B．（﹣2ab）²=4a²b²                                      

C．（a²）³=a⁵              D．3a³b²÷a²b²=3ab                                          

如图，直线AB，CD相交于点O，因为∠1+∠3=180°，∠2+∠3=180°，所以∠1=∠2．其推理依据是（　　）              

A．同角的余角相等     B．等角的余角相等                                        

C．同角的补角相等     D．等角的补角相等                                        

如图，有以下四个条件：①∠B+∠BCD=180°，②∠1=∠2，③∠3=∠4，④∠B=5，其中能判定AB∥CD的条件的个数有（　　）                                                                                            

A．1                            B．2                            C．3                            D．4

已知x=2，y=﹣3是二元一次方程5x+my+2=0的解，则m的值为（　　）                   

A．4                            B．﹣4                         C．                           D．﹣

计算2x（3x²+1），正确的结果是（　　）                                              

A．5x³+2x                    B．6x³+1                      C．6x³+2x                    D．6x²+2x

有下列几种说法：                                                                              

①两条直线相交所成的四个角中有一个是直角；                                             

②两条直线相交所成的四个角相等；                                                       

③两条直线相交所成的四个角中有一组相邻补角相等；                                  

④两条直线相交对顶角互补．                                                                  

其中，能两条直线互相垂直的是（　　）                                                

A．①③                       B．①②③                    C．②③④                   D．①②③④

．如图，下列说法错误的是（　　）                                                       

A．若a∥b，b∥c，则a∥c                             B．若∠1=∠2，则a∥c           

C．若∠3=∠2，则b∥c                                   D．若∠3+∠5=180°，则a∥c         

若|3x+2y﹣4|+27（5x+6y）²=0，则x，y的值分别是（　　）                         

A．                 B．                 C．                   D．