根据下列要求画图.
(1)如图(1)所示,过点A画MN∥BC;
(2)如图(2)所示,过点P画PE∥OA,交OB于点E,过点P画PH∥OB,交OA于点H;
(3)如图(3)所示,过点C画CE∥DA,与AB交于点E,过点C画CF∥DB,与AB的延长线交于点F.
   
(1)                         (2)                 (3)