This is a s____  of twin brothers, Justin and Paul. Their friend Susan calls them for h____ . Justin and Paul drive to Hill Building q____ . Three man in police uniform p____  them into a green van. They are not p____ . They are the robbers. The twin brothers aren't a____ . Paul opens the back door of the van w____  a knife. They take different r____  to the police station. They meet the robbers a____  in the police station. They are s____ . The policemen stop the van because the back door of the van is open.

①  OA＝OC    ②  AB＝CD    ③  ∠BAD＝∠DCB    ④  AD∥BC

请你从中选择两个论断作为条件,以“四边形ABCD为平行四边形”作为结论,完成下列各题：

下列判断中，正确的是（　　）

我们能看清楚远近不同的物体，是因为（    ）