According to a classmate who lived in the same village as Wang Xiaoshuang, after dropping out of school, Wang Xiaoshuang seemed to be a different person, silent all day long, and did not even say hello when she saw the villagers, but only stupidly did farm work at home.

This incident hit Teacher Li a bit hard, and she never had a smile on her face until the weekend holiday.

At noon on Saturday, after the last class, Niu Xiaoqiang picked up his schoolbag and went home.

Niu Xiaoqiang didn't feel much sorry for dropping out of school at the same table, because he had seen this kind of thing more than once. Many families will make this kind of forced decision when they are at the end of their lives, and they will naturally become accustomed to it after seeing too much.

"Mom, you rest first, I'll cook. When Niu Xiaoqiang got home, he threw down his schoolbag and ran into the kitchen to help his mother with housework.

Sun Mei smiled very happily: "Miwa, you are about to take the final exam, so let's go review your homework, you don't need your help with cooking." ”

Niu Xiaoqiang snatched the spatula from his mother's hand: "I'm not in a hurry to review my homework at this time." ”

Sun Mei couldn't help it, so she had to nod and agree.

After making lunch, Niu Xiaoqiang ran to the field under the scorching sun and called his father and eldest sister who were working in the field back. The four of them sat down at the table and ate with a hula la la hu.

There are only three dishes on the table, a stir-fried beans, a stir-fried water spinach and a plate of sour radish. Niu Xiaoqiang was the first to finish eating, he put the dishes and chopsticks away, got up and asked his father for advice: "Dad, if there is nothing to do in the afternoon, I want to go to Grandpa Fang's house for class." ”

According to the agreement between Fang Dongping and Niu Dazhuang, Niu Xiaoqiang had to go to him for classes every half month. It's been just half a month since the last time I went to class, so Niu Xiaoqiang took the initiative to make this request.

Niu Dazhuang was supportive of the class, he nodded, and advised: "Go, remember to study hard, don't mess around, otherwise Lao Tzu will break your legs." ”

"I knew I was going to study hard. ”

After Niu Xiaoqiang finished speaking, he packed up the things he needed for class and went out with his schoolbag.

At two o'clock in the afternoon, he came to the gate of Fang Dongping's house.

Fang Dongping was sitting under a big tree in the courtyard drinking a little wine. Originally, he didn't drink alcohol, but he was addicted to alcohol when Niujia Village was devolved. At that time, he was very depressed, although Niu Dazhuang didn't really criticize him, but he still couldn't forget the crazy faces of his students, and he was depressed all day long. It just so happened that every family in Niujia Village would brew baogu roast, and Fang Dongping borrowed wine to kill his sorrows under Niu Dazhuang's pest, and gradually became addicted to alcohol.

"Master, I'm here. ”

After Niu Xiaoqiang walked into the courtyard gate, he greeted Fang Dongping with a smile. Fang Dongping couldn't help but be stunned, and looked Niu Xiaoqiang up and down a few times: "The night before yesterday, your parents sent me pork, saying that you caught the wild boar, I couldn't believe it was true at the time, but now it seems that you have really become different from before, not only have your eyes become much more aura, but you don't talk knotted." ”

Niu Xiaoqiang didn't want to bother explaining how he became smarter, so he said haha: "Actually, it's nothing, Master, what are we going to talk about today?"

Fang Dongping pointed to a few bearings on the table with chopsticks: "Today is still the same, first of all, learn to find and find the defects on the bearings, this is a manual course, and then a cultural theory class." ”

Niu Xiaoqiang sighed, hung his schoolbag on the branch, walked to the basin and washed his hands, and then turned around to find the problems with these bearings.

In recent years, domestic fitters are very powerful, just by virtue of the feel, you can check whether there is a problem with the bearing, such as whether there are very small cracks, or the smoothness is not up to standard, etc.

Bearings belong to precision parts, every machine tool has this thing, if you want to control the machine tool well, you can't learn to check it.

Niu Xiaoqiang wiped his hand clean, then erected a bearing, stroked his fingertips back and forth on the bearing, and carefully observed it with his eyes while touching him.

Although Niu Xiaoqiang was a fool in the past, he still accumulated some experience in manual operation, but he was very unsatisfactory in cultural classes. With his subtle observation and feel, he soon found that the bearing was not smooth enough, and there were two places where it was slightly rough.

Don't look at such a small problem, if it is not corrected, it will accelerate the wear of the bearing, or metal fatigue, and even a serious production accident of broken shaft in serious cases.

After Niu Xiaoqiang pointed out the shortcomings he found, Fang Dongping nodded with a smile: "Well, check the next one." ”

In the next 20 minutes, Niu Xiaoqiang checked all the remaining bearings and found a total of 13 problems.

Fang Dongping was very satisfied with this, he drank the last sip of wine in the cup, got up and walked to the table, and the old and the young began to teach the cultural theory course in this humble courtyard.

In the past, Fang Dongping always talked about himself in cultural classes, although he knew that Niu Xiaoqiang could not understand, but he still spoke very energetically. Because it made him feel like he was going back in time and teaching students in a lecture hall at a university.

Today is different, Fang Dongping just wrote an equation on a simple wooden board, and Niu Xiaoqiang took the initiative to ask, "Master, what are you writing?"

Fang Dongping was stunned for a moment, then he remembered that the student in front of him was no longer the fool he used to be, and he explained with a happy smile: "This is a Bessel function equation. ”

"Master, what is a Bezier function equation?"

"To understand this, we first need to understand what a Bezier function is. ”

"Master, can you give me a detailed explanation?"

Fang Dongping couldn't wait for this, he nodded with a smile: "Of course there is no problem with this, the Bessel function is a general term for a certain class of special functions, without making specific conditions, the general Bessel function will be represented by the following ordinary differential equation." ”

After he finished speaking, he picked up a pen, brushed and wrote an equation in Niu Xiaoqiang's notebook, and then continued: "This is a second-order ordinary differential equation—"

"Master, what do you mean by the second order?"

Fang Dongping didn't rush to answer this question when he heard this, but said with a wry smile: "Xiaoqiang, let's start with junior high school mathematics, otherwise you won't understand what I'm talking about, it's just that I don't have relevant textbooks here, so it's not easy to do......"

Niu Xiaoqiang had already thought of this, only to see him smile, take out the math textbook used by the fourth sister Niu Dongxiang from his schoolbag, and put it in front of Fang Dongping: "Master, I have been ready for a long time." ”