听力资源简介：

upgrade　
(v.) 使升级，使升等

It’s always nice to get upgraded to first class.
能升级到头等舱是件很棒的事。

security　
(n.) 安全检查（处）

The man was stopped at security because he had a gun.
该名男子在安全检查处被拦下，因为他带了枪。