Mi Jun was taken aback, then laughed, finding her idea quite absurd.

"Are you a botany expert? You think the problem with our oxygen-deprived apocalypse lies in the light?"

He had a fever and was very weak; he would cough and wheeze for a long time after saying just one sentence.

Jiang Wan: "Yes, now all plants have stopped photosynthesis. I suspect the problem is light. It inhibits the absorption of blue-violet and red-orange light that plants need for photosynthesis."

(Just to correct you, in the first 66 chapters, the little sister was wearing red. Plants don't absorb much green light for photosynthesis. If you want to know more about photosynthesis, you can search it on Baidu. I won't go into details here!)

The US military officer chuckled and shook his head: "You doubt sunlight? You're too..."

Jiang Wan interrupted him directly, saying, "Don't be so quick to question me. You and I both understand the conditions required for plant photosynthesis. I can guarantee that the plant itself is fine, so what else could be the problem besides light?"

"And carbon dioxide, our air is now severely polluted, maybe the plants are poisoned?" Mi Jun still didn't believe that sunlight could be the root cause of the oxygen-deficient apocalypse.

"Although the air is toxic, it is full of carbon dioxide. Every living thing releases carbon dioxide when it breathes!"

Jiang Wan argued forcefully, "You're an optics expert. Whether there's a problem with sunlight or not, you can find out by doing one experiment, can't you?"

After a moment of silence, Mi Jun shook his head helplessly: "I understand what you mean. This experiment is not difficult, but I have contracted the plague and cannot return to my unit. My family does not have any equipment. Even if I wanted to help you, I am powerless to do so."

Jiang Wan then said, "You can put on a protective suit."

Mi Mang had been listening quietly the whole time, but now she stepped forward to stop him: "No, Uncle has a high fever that hasn't gone down, and he's coughing terribly. If we let him go out now, he really will die!"

The symptoms of this plague are in the lungs. He is now a critically ill patient and desperately needs an oxygen tube to breathe oxygen at any time. Going out to breathe toxic air with very low oxygen concentration would be the death of him!

"Don't worry, we've prepared an oxygen cylinder for him."

Jiang Wan glanced at Cheng Zhen, who immediately took out the prepared items. She was satisfied. Actually, if he hadn't prepared them, she could have provided an oxygen bottle herself, since she would definitely ask him to reimburse her afterwards.

"But my uncle has contracted the plague. Even if he wears protective clothing, will they let him in?"

Mi Mang was telling the truth, and the two exchanged a glance, looking somewhat embarrassed.

Jiang Wan frowned and asked, "How long has he been sick? Has he not been taking any medication?"

“We know that the herb Hundred-Petal Grass is useful, but where in the city can we find it? The pharmacies don’t have it either, so we’ve been taking fever reducers and cold medicine, but the medicine isn’t right for us and it’s not working!” Mi Mang was also very distressed.

"Are you alright?" Jiang Wan asked, noticing that she seemed to be in good spirits.

Mi Mang shook her head: "I was infected too, so I've been staying with my uncle these past few days." Her symptoms were milder.

Because she contracted the plague, she was kicked out of her home. Fortunately, her uncle took her in, and the two now depend on each other for survival.

Jiang Wan took out the Hundred-Petal Herb Juice from the tree hole space, pretending to take it out of her backpack, and handed it to Mi Mang: "This is the Hundred-Petal Herb Juice. Drink it and rest for a bit. We'll leave at dawn."

Although she was very anxious, she had to consider the patient's condition.

Mi Mang's eyes lit up: "Is this a Hundred-Petal Grass?!"

He immediately realized that the person standing next to her was a city guard, so it was no surprise that she had the Hundred-Petal Grass.

She immediately took it, but was stunned as soon as she touched it: "Oh dear, it's spilled!"

Then he quickly found two bowls and poured one for himself and one for his uncle.

Jiang Wan was taken aback. She had kept this medicine in the tree hole space for emergencies, so how could it have been spilled?

Her consciousness swept across the tree hole space and she suddenly felt that the withered tree hole seemed to have become greener. There were also some green liquid beads condensed on the hole wall. There weren't many, and she wouldn't have noticed them if she hadn't come to see them specifically this time.

Just as she was about to stop them, Mi Jun and Mi Mang tilted their heads back and drank every last drop of the Hundred-Petal Grass Juice.

She could only swallow the words that were on the tip of her tongue.

Cheng Zhen noticed her unusual behavior and asked softly, "What's wrong?"

Jiang Wan shook her head, not intending to tell him about the tree hole space, and only asked Mi Mang and Mi Jun: "How are you feeling?"

She added, "We dug up a lot of Hundred-Petal Grass from outside the city and brought it all into the city. Didn't you get any?"

Mi Mang shook her head: "At first, we were told that we could use crystal vouchers to buy things at the hospital, but later everyone went and didn't buy anything. After that, we stopped hearing about it."

Jiang Wan and Cheng Zhen exchanged a glance. Where did the Hundred-Petal Grass they had painstakingly dug up go?

Cheng Zhen clenched her jaw, having roughly figured it out.

He tidied up the sofa and let Jiang Wan lie down to sleep. Suddenly, Mi Jun sighed, "There's really a difference between having medicine and not having medicine."

"Uncle?" Mi Mang walked nervously into the room and asked, "Are you alright? Would you like something to eat?"

"I'm fine. I just feel much better after taking the medicine. My lungs and throat feel so cool." After saying that, Mi Jun said to her, "You took your medicine too. Go to sleep early."

Cheng Zhen slept on the sofa next to Jiang Wan. He was tall and had long legs, so he was not comfortable curled up in the short sofa and slept with his arms behind his head.

It was just the two of them in the living room, and it felt a bit awkward not to talk. So he whispered to Jiang Wan, "This medical book of Sun Sanhai is actually quite useful? Such unremarkable herbs, yet their medicinal effects are so good?"

Jiang Wan remained silent. The medical book was indeed as good as its reputation suggested, but she had a hunch that the medicine's immediate effects might be related to the green liquid in her tree hole space.

After Cheng Zhen finished speaking, he did not receive a response from her. He assumed that she had fallen asleep due to exhaustion from traveling, so he peeked in to check on her, then covered her with the thin blanket that Mi Mang had taken out, and turned off the living room light.

In the darkness, as he pondered the series of events that had unfolded, he instinctively felt that the city's various departments and systems were utterly corrupt. His volatile temper flared up for a while, but fortunately, Jiang Wan's familiar presence was there to soothe him.

Before long, they both fell into a deep sleep.

The two got up one after the other as soon as it was light the next day.

"Are you hungry? Would you like something to eat before you go?"

Jiang Wan shook her head: "I'm not eating anymore, let's hurry up."

"Alright." The air here is polluted; she might even catch the plague from eating. She should just bear with it and eat when she gets back.

He went in and called Mi Jun. Mi Jun woke up feeling great, his fever had gone down, and his throat felt better, though he still had a slight cough. He was amazed: "I never imagined these herbs were so miraculous!"

Cheng Zhen and Mi Mang were also surprised, but only Jiang Wan knew the truth: the sap in the tree hole was probably a rare and effective medicine.

She urged, "Let's go, where do you work?"