guard/ gɒːd /

1.noun [c] 
(sentry) 警卫

2.noun [u] 
(squad) 保卫队

3.noun [c] [BRIT] [Railway] 
列车员

4.noun [c] 
(protective cover) 防护装置

5.vt.[+building] [ entrance] [ door] 
守卫

6.vt.[+person] 
保护

7.vt.[+prisoner] 
看守

to be on one's guard (against)
提防
to lower {or} drop one's guard
放松警惕
to catch sb off (their) guard
乘某人不备
to be on guard
值班
to stand guard
站岗
I will guard it with my life
我将尽最大努力保护 它