Question: can a sub come back in in soccer

Answer: No, In association football, a substitute is a player who is brought on to the pitch during a match in exchange for an existing player. Substitutions are generally made to replace a player who has become tired or injured, or who is performing poorly, or for tactical reasons (such as bringing a striker on in place of a defender). Unlike some sports (such as American football, ice hockey or Kabaddi), a player who has been substituted during a match may take no further part in it.