One of the most important reasons why gas masks can protect against respiratory gases is that they can filter the air. The layers of filters in the gas mask can intercept any non-oxygen particles, so as to ensure that the human body can breathe the air correctly. However, in the process of filtration, even some of the oxygen is blocked, and it falls into a certain environment that causes hypoxia.

Liszt and the members of the Marine Corps are quite aware of this, especially in this cave where oxygen is insufficient, the use of gas masks is probably not deodorant, but a form of torture. Just take out the towel in the backpack, simply fold it into a triangular scarf, pour water on it and cover it in your mouth and nose, and hold your breath and wave the sapper shovel vigorously, as if you want to dig through this rock crack in the shortest possible time.

In fact, the progress of the project is also extremely fast, with only more than 20 people digging quickly, they have already penetrated into the tunnel nearly 20 meters away. In particular, the tunnel that seems to be a rock crevice that seems to be dug diagonally upwards shows that the opening on the outside of the mountain must be in the area where it is halfway up the mountain.

However, it is no longer a person digging in front, because the bat droppings dug up have already filled the bottom of the rock crevices, and someone must quickly sapper shovels behind to sweep the back to keep the tunnel, which is less than half a meter wide, from being re-blocked by the bat droppings dug up above. Even in the middle of the cave, more than a dozen piles of bat manure excavated in the rock crevices are piled up there, and if they are not cleaned up, it is estimated that it will be a joke to want to live in the future.

As they dug in, the Marine at the front narrowed his eyes slightly. After digging a slight bend. His gaze had seen it right in front of him. In that football-sized vent. There was already a little light, which made his eyes widen, and he shouted to the back: "Hey, it's right ahead, I saw the sunlight in front of me!" ”

As he spoke, he exerted himself quickly, and large chunks of bat droppings quickly collapsed and fell off with the sharpness of the sapper shovel. And the clarity of the sunlight in front of him became more and more obvious. Even according to his calculations, as long as they dig hard for a few minutes, about four or five meters, they can completely bury this rock crevice that was completely buried by bat droppings and reopen a road to the outside world!

"Good, we were right about it!"

Liszt also clenched the sapper shovel in his hand, slowly straightened his waist next to the dozen piles of bat dung, and looked at the Marines who were also busy around him, but there was a little more smile on his face. Turning his head to Karl, who was also looking at him next to him, he couldn't help but nod and said, "As long as we can open a new tunnel." Then the ventilation problem in this cave can be solved! ”

"Solving the ventilation problem is only the first step, and we still have piles of bat droppings that need to be cleaned up. Especially now, it seems that the amount of work is not too small. ”

Nodding slowly, Carl also gently straightened his waist, bending over for nearly half an hour in a row, making his spine a little tired. Rubbing his back vigorously, he looked at the dozen piles of bat dung in front of him, and the tactical flashlight in his hand also swept towards the entire inside of the cave, but a wry smile appeared on his face: "And on the ground in most areas, we haven't cleaned those bat dung, if nothing else, we need a week's workload to complete it all." ”

"A week? No, it's been too long. ”

His brows were also slightly furrowed, and Liszt turned his head to look at the more than a dozen piles of bat droppings in it, which were only dug out of the rock tunnel, plus the more than 1,000 square meters of karst cave ground, it is estimated that there will be no problem with more than a dozen piles. Sighing slowly, Liszt stuck the sapper shovel on the pile of bat dung more than a meter high beside him, and nodded slowly: "It's time to increase some manpower." ”

If you want to completely clean the cave of more than 1,000 meters, it is really impossible to do it without a week. Besides, more than 20 of them are not robots, and if they want to clean up and take care of them night and night, they can't stay in this rancid cave at all. Especially looking at this huge cave space, Liszt thought about it in his heart, and still said to Karl: "Continue to recruit twenty people to form a platoon-level force, and forty people take turns to clean up, which should shorten a lot of time." ”

"Captain Liszt, we've dug through this rock crevice!"

A cheer of surprise appeared in the cave, which immediately interrupted the conversation between Liszt and Karl. In the half-meter-wide cave rock crevice, the soldier with a towel still tied to his mouth and nose was carefully sliding down and taking a deep breath, but the still strong rancid smell made him cough instantly, and at the same time beckoned to Liszt: "There is a cliff above this rock crack tunnel, and you can even see the entrance of the cave when we came from more than five hundred meters away!" ”

"What?" Liszt's eyebrows furrowed slightly, and he immediately walked quickly towards the rock crevice, and Karl behind him also quickly followed. The cool breeze also seemed to appear in the tunnel of the rock crevice, blowing and removing some of the rancid smell. And he strode forward, striding straight up the sloping tunnel and striding towards the glimmer of light at the top.

The tunnel is also not crowded, it is basically half a meter wide and more than two meters high, as if it were an eye with a prick up. And Liszt quickly stepped up in this tunnel, and after climbing a few slopes of about seventy degrees, there was already an obvious light in the tunnel in front of him, and even the tactical flashlight in his hand could not hide it.

"There really is another exit to this cave!"

And the freshness of the air has completely driven away the putrid smell of bat droppings, Liszt walked quickly towards the light, his eyes couldn't help but squint slightly, when he gradually adapted to the light, he slowly opened his eyes, looking at the lush primeval forest of the Rocky Mountains outside, and the blue sky and white clouds, and couldn't help but take a deep breath: "It's really out!" ”

But a strange sound made Liszt's ears move slightly involuntarily, but he raised his head instantly, and a dense data stream also exploded in his two pairs of eyes, and between the blue sky and white clouds, a F-15 fighter of the United States Federation was whistling into the distance, and the extremely fast speed had already pulled a long line in the clouds. But it was definitely not a normal cruise, because just behind its ass, two Soviet MiG-25s were fighting, biting tightly in the back and launching an attack stance from top to bottom! (To be continued.) )