However, when the black rock gate was completely raised, there was no exit they expected, and instead there was another stone wall, which was also completely black, but there seemed to be a bright spot on it.

Obviously, this bright spot is much brighter and smaller than the ball used on the wall.

"What's going on?" Yun Yanuan said puzzledly.

Seeing Yun Yanuan reversing the rudder, the fat bear immediately slapped his thigh and said to himself: "Why did I forget to try to reverse the rotation, it turns out that this is the key to open the main door." ”

A few people hurriedly followed, originally thinking that even if they couldn't get out, there should be a similar passage, but unexpectedly, the door opened, but there was another stone wall.

The fat bear was immediately unhappy, and scolded: "Oh, I bought a watch last year, how can I play people like this?" Behind a door, another door, isn't this salt in the sea, idle! ”

It's very unreasonable, no one would make a building like that, because it doesn't make any sense at all, but the truth is right in front of you, and you have to accept it.

Maya pointed to the pattern on the ground and said, "Look, what is that?" ”

A few people followed Maya's fingers and looked down, there was a compass pattern on the ground, the middle was divided into yin and yang, the second layer performed five elements, the third layer was divided into innate gossip, and the fourth layer was divided into ten divisions, but those patterns were not recognized, the fifth layer and twelve divisions were still some ghostly patterns, followed by twenty-four divisions, seventy-two divisions, and finally eighty-one grids.

If you ignore those strange patterns, just these partitions are very neat and even, and you can feel the neatness and uniformity without using a ruler.

The fat bear hurriedly squatted down, touched the lattices, and found that they were carved and could not be moved, this was not a mechanism, just a figure.

So he shook his head and said, "It's just a carving, you can't move, the switch isn't here!" Look elsewhere! ”

Everyone looked around, except for the rudder, there was nothing to move, and they couldn't help but focus their eyes on the pantuo again, Yun Yanuan shook his head and said: "Don't study that thing, I've already turned my head, it's definitely not that thing!" ”

The fat bear didn't believe in evil, so he lifted it up and down with his hand on the rudder plate, and found that he didn't move at all, so he stopped his hand and shook his head, indicating that he had no tricks.

Kexin squatted down, with a puzzled face, groping on those patterns, and muttered to himself: "Maybe the problem is still on these groups." ”

As he spoke, he walked around the patterns, and suddenly wondered: "Have you noticed that the light shining through the small hole in the high part of this door is flickering and swaying from side to side, while the other is moving slowly, although the speed is very slow, but it does change!" ”

A few people didn't pay attention at first, so they naturally couldn't remember this, and after hearing Kexin's words, they all focused on the two spots of light on the ground to see if it was the same as what Kexin said.

Sure enough, after a while, there was a spot of light that did move some positions slowly and steadily, although it was a short distance, but it did change, and several people were happy and sad.

Happily, this light spot moves, then it means that this light is likely to be shining in the sun, then outside this black door, it must be the exit, and the sad thing is that I don't know how to open the door.

"Damn, this is really urgent, according to Master Xiong outside, I guess it should be sunshine, but we can't get out!" The fat bear sat on the ground and said angrily.

"Don't make any noise, I'll think about it!" Kexin was thinking about the problem, and was interrupted by the loud voice of the fat bear, so she scolded Jiao, and said, the little girl learned from Brother Hugh, sat cross-legged on the ground, closed her eyes and began to meditate.

The bear fat man was choked by Kexin, and immediately stopped making a sound, even recovering his breath, which made people want to laugh.

After about ten minutes, Ke Xin suddenly opened his eyes, glanced at the light spots on the ground, and shouted at the bear fat man: "Bear fat man, you go and find a way to block the light through the small hole!" ”

When the fat bear heard this, he didn't think about it, and shouted directly: "Okay, look at me!" The guy didn't ask the reason, if you asked me to block it, I would block it, but when he walked to the black stone door, he was dumbfounded, and when he turned around, he smiled embarrassedly: "This is at least four or five meters high, I can't reach it!" ”

Yun Yanuan snapped his fingers and said, "Let's stack Arhats!" But why plug it? ”

The girl thought of a way to plug the hole, but then she remembered and asked, why do you want to plug it.

But Xin didn't elaborate, only said: "It is estimated that if it is blocked, the door will be opened!" ”

"I don't understand!" Yun Yanuan shook his head vigorously and said.

The same goes for a few other people, a head of mush.

Ke Xin looked at the light spots on the ground and said: "I just guess that this black door is like a two-story security door in our house, and the hole is a sight glass, but it is not used to see if it is a stranger who knocks on the door, but to monitor the sun." ”

"Watching the sun?" Diana said suspiciously, "Why?" ”

Ke Xin waved his finger at the wide corridor behind him, and then said:

"If you look at the scale of this underground city, if my guess is correct, we just walked around the outskirts of this underground city, and you can imagine that its scale is definitely almost the size of a small city.

What kind of person would be willing to spend such manpower and material resources to build such an underground city? Even if it's a desert outside, with such manpower and material resources, it's not the same as living well? ”

Fat Bear still felt that this thing was like a three-defense fortification, so he said: "I always feel that it should be a fortress to hide from war." ”

Ke Xin shook his head and said:

"No one builds an underground fortress, and it is a waste of time and money to be willing to spend so much material resources to build these longitudinal corridors.

Yun Yanuan smiled: "Then I understand, these people live underground, and then install security doors for their city!" Isn't that what it means? ”

Ke Xin knew that Yun Yanuan was ridiculing, but he said without denial: "Yes, whether it is an anti-theft gate or a city gate, in short, it is a security measure!" ”

"But aren't the gates all for defense against foreign enemies?" Diana thought for a moment and asked.

Ke Xin nodded and said: "That's right, if you get two layers of city gates, it must be set up to prevent aggression, but if it's just to prevent foreign enemies, one layer is enough, and it's better to thicken it than to repair two gates, right?" ”

Seeing that a few people didn't speak, Ke Xin said with certainty: "So, this door with a small hole in the sight glass, while preventing aggression, the main role is to monitor the sun!" ”