In this task your given two statements in Chinese. You must judge whether the second sentence is the cause or effect of the first one. Label the instances as "cause" or "effect" based on your judgment. The sentences are separated by a newline character.

旅客到达边境。
巡逻员检查了他们的护照。
effect

桌子摇晃着。
地板不平。
cause

电影票卖完了。
这是电影的首映日。

cause