【答案】解胡衡:∵GH⊥CD,(已知)∴∠CHG=90°.(垂直定义)又∵∠2=30°,(已知)∴∠3=60°.∴∠EHD=60°.(对顶角相等)又∵∠1=60°,裤山做(已唯伍知)∴∠1=∠EHD.∴AB∥CD(同位角相等,两直线平行)