Upon hearing Ling Chen's words, everyone focused their gaze on him and asked, "What's wrong?"
"Look at the ground," Ling Chen pointed to the ground beside the door and then wiped the dust away with his hand. Suddenly, two relatively deep marks appeared on the ground. He Honggang looked at those marks and asked, "What is this?"
"These should be marks from friction against the ground when the door opens," Ling Chen explained. "Did you notice that these marks are quite deep? If this stone door had only been opened once, the marks wouldn't be so deep; only after repeated friction would these grooves become this deep."
"Repeated friction?" Upon hearing Ling Chen's words, everyone immediately understood what he meant. "You mean... this stone door has been opened many times?"
