Yi Cheng was still a little dazed when he was called up from his seat.

After all, in the dream world, he listened carefully and took notes, and he would not be suddenly called up from his seat by the teacher.

Two different variables, the results obtained are completely different.

He also wondered if he should listen carefully to the lecture instead of studying in his dreams.

But it would be a waste to give up 3 times the study time in the dream.

"Yicheng, you come up and do it." With the teacher's kind smile, Lu Xinyu held the signal pen in his hand and motioned for Yi Cheng to come up.

Everyone watched him with bated breath.

It's over, I sleep in class, and I'm still being caught.

Some people watched everything silently with the expression of watching the play.

Yi Cheng left his seat, took the signal pen from Lu Xinyu's hand, and walked to the whiteboard.

There is a chemical equation written on it in neat handwriting-

[When calcining chromite, a chemical reaction occurs:

Fe（CrO2）2+Na2CO3+O2——Fe2O3+Na2CrO4+CO2

】

"Trim equation." Lu Xinyu said lightly.

Yi Cheng nodded, picked up the pen and began to answer.

The students below were also doing their own calculations when they saw him doing the calculations.

Chemical equation balancing is a compulsory question in the college entrance examination, and the key to this question is to find a way to balance.

The difficulty is that for most students, balancing takes time, especially for some elements with multiple valences, such as iron, which have both positive 2 and positive 3 valences, and must be balanced with conservation of charge.

After 2 minutes, Yi Cheng walked down from the whiteboard.

"Huh?"

Bai Jingxue was just halfway flat, and looked up at him blankly.

Is this guy done?

The others were also surprised.

Yi Cheng met everyone's eyes and silently walked to his seat and sat down.

This guy can immediately enter the state to answer questions when he sleeps in class, and I'm afraid few people can do this kind of thing.

As for whether it's right or not-

The whiteboard reads the whole problem-solving process:

[Assuming that the coefficients before each molecule are A, B, C, D, E, and F, respectively.]

So, get the equation:

AFe（CrO2）2+BNa2CO3+CO2——DFe2O3+ENa2CrO4+FCO2

The set of equations is obtained according to the law of conservation of mass:

A=2D

2A=E

4A+3B+2C=3D+4E+2F

2B=2E

B=F

Then let E=1

Obtain a system of multivariate linear equations:

A=2D

2A=1

4A+3B+2C=3D+4+2F

2B=2

B=F

Solution:

A=1/2

B=1

C=7/8

D=1/4

E=1

F=1

Then multiply by the least common multiple of 8

Get A=4

B=8

C=7

D=2

E=8

F=8

The trim result is:

4Fe（CrO2）2+8Na2CO3+7O2——2Fe2O3+8Na2CrO4+8CO2】

A few good chemistry scores also came up with answers, but they were more than ten seconds later than Yi Cheng.

"Correct." Lu Xinyu laughed calmly.

That's right!

"me, is this guy a genius?"

Someone muttered quietly.

In their consciousness, they can shout and answer at any time when they sleep in class, and they can get full marks casually when they have fun, and this kind of thing only exists in legends.

A lot of geniuses who don't seem to study much actually work harder than anyone else at night.

Lu Xinyu smiled when she saw this.

"Good. Universal balancing. ”

She nodded to Yi Cheng, seemingly satisfied.

"That's a good answer. Dozing off in class isn't a good thing, though, and I'd rather you spend more time in class than stay up late at night. Let's not take it as an example, got it? ”

Lu Xinyu attributed the reason why Yi Cheng slept in class to the fact that he usually worked too hard, and stayed up late at night to study, resulting in no energy during the day.

After all, this student was raised by them, and Yicheng's learning effort is obvious to everyone.

No one can work harder than this guy.

However, even if it is too much machine, overloading like this will cause problems one day.

Thinking about it this way, it's a little painful.

There is no teacher in this world who deliberately makes things difficult for his classmates, and no teacher deliberately wants to get along with his students because of a trivial matter.

That kind of thing only exists in Xiao Baiwen, who pretends to be forced to slap his face.

Even a teacher like Lu Xinyu, who is strict with his students, hopes that his students will be good.

Since Yi Cheng answered the question correctly and gave him a proper reminder, he can just click until he finishes.

"Hmm."

Yi Cheng nodded and began to listen carefully.

"The universal trim method used by Yi Cheng, although it is not the fastest trimming method, is worth learning from, and you can use his method if you encounter chemical equations in the exam in the future."

Lu Xinyu returned to the whiteboard and began to explain to everyone.

With her explanation, some people suddenly realized that it was not because Yi Cheng was a genius that he could brush up and do the questions when he slept in class.

In fact, this kind of problem is a breeze for an honor student like Yi Cheng.

The so-called universal trim method is actually to use the law of conservation of mass and charge to convert the trim of chemical equations into a system of multivariate equations in mathematics to solve.

And this solution is the only one.

Elementary school students can also answer quickly.

"Yes, it's a mathematical talent." Xiaobai praised Yi Cheng and winked at him.

But Yi Cheng couldn't be happy.

Out of respect for the teacher and the class, he will not be able to enter the dream state during class in the future.

Then three times as much time in the dream can only be used during the rest time.

It's frustrating to lose so much study time for no reason.

……

After successfully finishing the morning class, Yi Cheng hurriedly followed Xiaobai to finish eating, and then ran back to the classroom for a lunch break.

Xiaobai stared at him with wide eyes in confusion.

"Do you have narcolepsy?"

In addition to going to class, it is sleeping, which is even more excessive than her.

But she didn't think about it so much, she played with her phone for a while, and then fell on the table.

In the afternoon, there is a weekly swimming lesson time.

After a short dream study, all the students in Class 3 put on dead water and gathered by the pool.

Ming Feng Secondary School is very different from other secondary schools:

Although many middle schools also have swimming pools, because of drowning incidents, they are almost not open to students for reasons of protecting the safety of students, even if it is a routine swimming lesson, it must be supervised by several teachers at the same time, and once it falls into the water, it must be closed for a year and a half.

Swimming lessons are a form in 90% of secondary schools, and two or three sessions are taught throughout the middle school career.

And there is another important reason for not doing swimming lesson training -

In the group of high school students, young boys and girls are relatively close to adults, and they are in the budding period of adolescence, so they have little contact with the opposite sex, and it is inevitable that some ideas will arise on this occasion.

In order to avoid puppy love and things that cannot be written about the starting point, the vast majority of schools will not offer swimming lessons.

Mingfeng Middle School is special here-

Because it has trained several swimming champions and diving champions in the past, and has sent talents from the swimming and diving circles to the country, swimming lessons have been promoted and supported here.

Coupled with the first-class swimming facilities and excellent coaches and standardized management, there have been no drowning incidents in the past ten years.

Parents can rest assured that there are many remarks that exercise can better promote children's learning, making swimming lessons a compulsory subject in Mingfeng Middle School.

But Yi Cheng didn't think so.

Physical education lessons, swimming lessons, etc., it's such a waste of time.

What's more, he's a landlubber plus sports idiot.

Oh yes, before yesterday.