I.
noun
ADJECTIVE
▪ heightened , high
▪
The country has put its troops on high ~.
▪ full
▪ amber , orange , red , yellow
▪
His sudden disappearance triggered a red ~ among his friends.
▪ nationwide
▪ bomb , fire , flood , pollution , security , terror
▪
A security ~ was issued after four men escaped from the prison.
▪
Receive regular email ~s about breaking news.
VERB + ALERT
▪ issue , put out , raise , sound
▪
They rang the bells to sound the ~.
▪ spark ( esp. BrE ), trigger
▪ call off
▪
The ~ was called off when it was found that the bomb was not live.
ALERT + VERB
▪ go out
▪
A nationwide ~ went out for three escaped prisoners.
PREPOSITION
▪ on the ~
▪ ~ for
▪
You should always be on the ~ for anyone who looks suspicious.
PHRASES
▪ be on full ~
▪
The security forces are now on full ~.
▪ place sb on ~ , put sb on ~
▪
Thousands of police were put on full ~ at all main roads leading to the city.
▪ keep sb on ~
▪ a state of ~
▪
The army was yesterday placed on a state of ~ in case of more riots.
II.
verb
Alert is used with these nouns as the object: ↑ authority , ↑ police , ↑ press
III.
adj.
VERBS
▪ be , look , seem
▪ become
▪ remain , stay
▪ keep sb
▪
The machine should help to keep the pilot ~.
ADVERB
▪ extremely , fairly , very , etc.
▪ fully
▪ immediately , instantly , suddenly
▪
There was a noise outside and he was suddenly ~.
▪ always , constantly
▪ mentally
▪
He was as mentally ~ as a man half his age.
PREPOSITION
▪ to
▪
Climbers need to be ~ to possible dangers.
Alert is used with these nouns: ↑ expression , ↑ reader