If you are careless it means that you do not pay attention to what you are doing,so you make mistakes or have accidents.如果你careless,那指的是你做事漫不经心,你会出差错的。 If you want to say that you have no worries If you are careless it means that you do not pay attention to what you are doing, so you make mistakes or have accidents. If you are careless, that means you are doing something careless and you will make mistakes. If you want to say that you have no worries