It's different to question witnesses. Because the personal freedom of witnesses is not restricted, sometimes only one investigator is present when committing a crime. For example, a policeman was robbed on his way home from work, a foreign tourist saw the incident, and people had to leave the country after 1 hour. If it is mandatory that one person cannot take evidence, it may lead to the inability to obtain witness testimony afterwards. At the same time, the Criminal Procedure Law has made supplementary provisions on written testimony. If the parties and defenders have objections to the written testimony, and the testimony has a significant impact on the case, the court can summon witnesses to testify in court, which makes up for the problems that may arise from the right to act in a hurry.