题目

    CHICAGO (AP) On Jan.  l，an order went into effect requiring that every checked bag at more than 400 of the nation's commercial airports be screened for bombs and weapons.     Sunday was expected to the heaviest travel day since Jan.  l. Yet spot checks on Sunday at several  of the nation's airports showed no major delays caused by the new security measures.     At the international terminal for Northwest Airlines at John F.  Kennedy International Airport in New York, passengers waited up to 30 minutes longer than usual.  Their bags were sent through giant screening machines图是小红同学设计的用U形管压强计研究影响液体压强因素的实验：请你在认真观察每个实验的基础上，回答下列问题：实验1是想验证________相同时，液体的压强与________的关系；实验2是想验证________相同时，液体的压强与________的关系；实验3是想验证________相同时，液体向________的压强都________．