They drove to the experimental field and swiped their ID cards to take on the last day's work. Two hours later, they received the certificate from the old man and went to the place he mentioned to upgrade their identity cards. After the upgrade, they would become permanent residents of the fourth base. If they did not have permanent identity cards, did that mean they could not stay in the base? Actually, it was possible. After all, whether it was in the past or now, there would always be illegal ways.
However, every three days, there would be security guards patrolling the fourth base with a card reader, or they would go door-to-door. They might just randomly pick someone on the road for a spot check. If they were found to have no ID card, there were only two options—do double the work or be expelled from the base.