We need to 'alert' the public 'to' the dangers of these chemicals. [=we need to tell the public about the dangers of these chemicals]
Several neighbors 'alerted' the authorities/police when they noticed strangers acting suspiciously.
The nurse kept/stayed 'alert' for any change [=watched for any change] in the patient's condition.
(..) Why not? Well, for one, his name rhymes with "butt." I don't care. I'm gonna have a big, fat, Egyptian wedding. Spoiler alert, King Tut dies young. Are you sure you've thought this through? Oh, trust me, I've thought it through. I'm getting everything. (..)2014 Mr. Peabody & Sherman