根据下图，完成下列推理过程．

(1)∵∠1＝∠A(已知)， ∴AD∥BC
.(________________________________________________________)
(2)∵∠3＝∠4(已知)，∴CD∥AB
.(________________________________________________________)
(3)∵∠2＝∠5(已知)，∴AD∥BC
.(________________________________________________________)
(4)∵∠ADC＋∠C＝180°(已知)，∴AD∥BC
.(________________________________________________________)