safety意为保险机、中卫时，是可数名词

a safety (catch) （枪，炮的）保险机

a safety (美式足球) 中卫

意为安全、保险时，是不可数名词

相关介绍

Production has been suspended while safety checks are carried out.

在进行安全检查期间生产暂停。

He didn't seem in the least concerned for her safety.

对她的安全他似乎一点都不担心。

Firefighters formed a human chain to carry the children to safety.

消防队员组成人链把孩子们救到了安全的地方。