护栏，用英语怎么说呢？the guard rails!

1. 在此表达里，guard之意非"卫兵；守卫"也，其意为a device that protects a dangerous part of something or that protects something from getting damaged保护装置；保护用品；保护器

例如：a fire guard火灾防护装置

a trigger guard（锁定）枪（扳机）的保险

The helmet has a face guard attached.这个头盔带有一个防护面罩。

2. rail, 也非'铁轨'，而是指a horizontal bar fixed in position, especially to a wall or to vertical posts, used to close something off, as a support, or to hang things on（尤指固定在墙上或竖杆上的）横杆，栏杆，扶手

3. rail做动词，还可以指to complain angrily谴责；抱怨

例如：He railed against/at the injustices of these safety/health/traffic/fire/security regulations

他强烈谴责这些安全／卫生／交通／消防／保安条例的不公正。

4. go off the rails，用于informal场合，意为：to start behaving in a way that is not generally acceptable, especially dishonestly or illegally举止怪异；越过道德底线，行为不轨

例如：He went off the rails in his first year at university.

他刚上大学一年级行为就很出格。

（译例选自剑桥在线词典）