These men are dangerous so you’ll need to be on your guard.
这些人很危险,所以你要提防着点。
Something in his tone put her on her guard.
他说话的语气使她提高了警惕。
Examples from the Corpus
put ... on ... guard• The hostilebarkput Miguel on his guard.• Anyway after that he put Raimundo on guard with a gun.• Enright at the Freie Universität in West Berlin, and that information immediately put me on my guard.• Whatever, it puts you on your guard.• The polltaxdisaster should surely put us on our guard.• And officers - some armed - were put on guard at Aylesbury policestation.• Detectives feared he was out for revenge and armed police were put on guard at police stations.