C46 Surprise or Shock?

"?" There seems to be the sound of a door opening downstairs … " Miao Xu frowned slightly.

The sound of the door opening? Lin Meixin and Lin Meiyu were both stunned for a moment. Mrs Zhang, who was in charge of household chores, had already left. Who would open the door at this time? They also pricked up their ears and heard the sound of the automatic door opening outside