Again, they are all close to the same. The only difference is that to be placed under arrest is more the passive voice. To be under arrest - present tense Ex. Stop! You are under arrest. To be arrested - past tense. Ex. He was arrested yesterday at 4:00.

You can use all three of these. "She was placed under arrest" is perhaps a bit more formal and emphasises the involvement of others (i.e. police officers). "She was arrested" means the same. You can also "be under arrest": for instance a police officer could say, "You are under arrest", or you could ask, "Am I under arrest?"

Hello, To be placed under arrest refers to the apprehending or detaining of the person, in order to be forthcoming to answer an alleged or suspected crime. To be arrested is to be taken to a police station, held in custody in a cell and then questioned. Yes, you can use 'be under arrest', depending on the message you're trying to pass across. For example, Peter is under arrest. I hope this answers your question. If you’d like to practice speaking. I’d be happy to help you develop a study plan. Feel free to view my teaching profile and class offerings and send me a message if you think I can help you. Regards