The mobile phones of the two are of the same brand and similar in appearance, which is really indistinguishable at first glance. While Sang You breathed a sigh of relief, he asked curiously, "Then what are you calling me now?" ”

"Backup."

“？”

The world is really uneven, even if it is born by one parent and dad.

Sang You: "Where did you get the spare machine?" How do you have a spare machine? ”

"Uncle's old phone." Sang Luo didn't want to talk more, so he hung up the phone after speaking.

Sang You stared at her phone and fell into self-doubt, normally, she should be twenty-four years old now, how old is the little brother...... Coming? Forget, but it should not be more than fifteen.

The Sang Luo in his memory has two personalities, withdrawn and indifferent to the outside, and vicious and intimidating to the inside, and his personality is not very pleasing. She has long forgotten what Sang Luo looks like in adolescence, but according to her current understanding, it is very similar to the image in her impression, and this person has really not changed.

She put her phone away and made eye contact with Ning Yan again.

“…… What did you just ask? ”

"How old is my brother?"

“……”

That's what she couldn't think of just now.

“14？” Sang You wasn't so sure.

Ning Yan was shocked: "You don't even know how old your brother is?!" ”

It's also strange to say, Sang You can't remember Sang Luo's age accurately from beginning to end, she has always felt that the age calculation is very complicated, there is a difference between virtual and real, and there is also a difference in the Gregorian calendar, but she is very sure of Sang Luo's grade.

-

The textbooks that should be bought were basically bought, and with the textbooks given by Senior Sister Lin Qiaoyan, Sang You began a round of review in his own sense. For liberal arts, she is accustomed to drawing logical diagrams, involving several books at the same time, divided into different modules to reason and supplement each other, and then memorize.

This method is somewhat similar to the memory palace, she has built her own palace, from the beams and tile joints to the tile railings, there is a set of logic that belongs to her.

The advantages are clear, the advantage is that the memory is firm, the thinking is divergent when answering the questions, and it can be constantly supplemented and complete; The disadvantage is that there is a lot of thinking, and it takes a lot of time just to build the framework.

Sang You pondered the interrelationship between geography, land, water, and native life and the small branches involved for two days, brainstorming in his brain, thinking that his brain was about to crack.

Why is geography called geography? Because there is no heavenly reason.

After constructing the prototype of thinking, I didn't get much sense of accomplishment from geography, and when I encountered mathematics, I collapsed.

Usually at noon in the library, she uses it to learn mathematics - review and preview, consolidate mistakes, check and fill in gaps in online classes, time-limited training, topic reinforcement, and problem specialization.

Sang You's all-round learning of mathematics without dead ends has little effect, and he can pass but can't get high scores.

To sum it up, the results are mediocre and not worth mentioning.

With this math score, it is difficult to skip a grade.

Sang You is studying a derivative problem, the first small problem is to find the monotonic interval and extreme value of the derivative f(X), the basic problem, and another function to find the derivative can be solved.

The second question is the proof question.

She used a lot of common problem-solving methods, and she couldn't write a small part anymore.

It's just struggling.

Keep thinking.

Twenty minutes later, still clueless.

Sang You held her head with her hands, staring at the topic and constantly changing her thinking, but she was killed by a wall on the south wall, and after hitting it all over at 360 degrees without dead ends, Sang You understood that this was a topic that she couldn't climb.

Sang You glanced at her watch, forty o'clock, thirty-five minutes before class, usually at this point she would choose to take a nap, wake up at two o'clock and return to the classroom from the library, basically awake during the walk, and then ready for class.

Go to bed.

Sang You lay down.

Within five minutes, Sang You couldn't help but open his eyes, his eyes full of resentment.

Still unwilling!

She straightened up and picked up the pen and tried to write again, but now she couldn't sleep at all, and she was angry.

I can't even write about it!

Mathematics is simply the enemy of life, and when you can't write, you either want to sleep or get angry.

At this time, the library was silent, and most people were leaning over to sleep at this point, their backs rising and falling slightly with their breathing. A few are still writing, but the sound is very small.

Quiet and relaxing.

However, in this quiet atmosphere, a dynamite barrel was almost blown up, and finally the explosive barrel got up and went to the toilet to wash his face and regain a little sense.

On the way back, Sang You's eyes involuntarily looked at the end of the long table by the window, the place was empty, and she was lost for a moment.

After the gaze moved, he paused suddenly, and joy crept up in his clear eyes.

The poet said that when I met you, it was the wind of the wilderness that broke into my heart, and the snow between my eyebrows that melted into my eyes.

It is difficult for Sang You to describe the feeling of that moment, but she only feels that the moment she saw Zhou Yan, the years were calm, time slowed down, and the frivolous woodtops outside the window witnessed the joy of the girl, shining in the sun.

When he reacted, Sang You was already holding his schoolbag and sitting opposite Zhou Yan with the scroll.

Zhou Yan was sleeping.

Sang You stared at him unscrupulously for a while before lowering his eyes to look at the derivative problem.

I can't read, I can't write, and I can't sleep.

Sang You, who was in a trilemma, began to be in a daze, she leaned on the back of the chair, her eyes looked forward naturally, and her eyes were out of focus.

Sang You's concentration is very high, and once he starts to devote himself to something, his ears and eyes are closed, and he almost enters a meditative state in a daze. I don't know how long it took, but there was two knocks on the table in front of me.

"Huh?" Sang Youyou suddenly came back to his senses.

Zhou Yan's hand has not been withdrawn, his knuckles are slightly bent on the table, he has just woken up, his expression is worried, there is a kind of lazy meaning, and his voice is low when he speaks, I don't know if it is because of the environment of the library, or because he has just woken up.

"What's the fuss?"

Sang You looked at him stunned, and it took a long time to notice that her eyes were sour, and she blinked, so stimulated that tears almost flowed down.

"Do the question." She said.

Sang You took off her glasses and rubbed her eyes, feeling that her eyes were going to be wasted, she didn't know if she was open or closed when she was in a daze just now, and whether she blinked when she opened her eyes.

Zhou Yan looked at her red eyes, and looked inexplicable: "Can't do it?" ”

"No, it won't." Sang You said with annoyance.

Zhou Yan raised his fingers, pressed the roll, dragged the roll, looked at it for a while and said, "Come here." ”

"Huh?"

Zhou Yan raised his eyelids: "Come and sit next to me." ”

Sang You sat down in a regular manner, and saw Zhou Yan pick up the pen and start writing the steps on the scratch paper.

"The answer to the first step can be found with a part, another function can be set to find the derivative, clarify the range of X values, make a third derivative, and use the Lobida rule to determine whether the limit exists, and indirectly prove it."

Zhou Yan wrote the steps while talking about the short answer ideas.

“……”

It turns out that the feeling of knowledge flowing through the brain is like this, it turns out that this is called the left ear in and the right ear out, and it turns out that this is an indestructible knowledge barrier.

She understands another function, she also understands the third guide, and although the law of Lobida is the content of advanced mathematics, it is still basic, and she barely understands it.

But when they were all connected, she was confused.

Zhou Yan dropped the last stroke and pushed the scratch paper over.

Sang You subconsciously looked down, and first sighed that Zhou Yan's font was beautiful, and he was very scholarly at first glance. Second, look at what he wrote.

Zhou Yan writes concisely, but there are all the steps that should be taken. Sang You studied for a long time, watched Zhou Yan's train of thought go down, and suddenly felt the enlightenment and woke up, and there was a kind of shock of listening to thunder in a silent place.

The feeling of this kind of knowledge hitting the soul is really wonderful, Sang You's eyes lit up, and she hurriedly pointed to the paragraph where Zhou Yan used the law of Luobida: "I remember that the law of Luobida has conditions for use. ”

"It can't be used to solve the limits of inequalities."

Zhou Yan looked at her happy appearance and felt a little surprised.

He pays attention to efficiency in doing questions, often uses the fastest method, the purpose of the idea just now is to expand Sang You's knowledge, and he doesn't expect her to understand, because he remembers that the derivative is the knowledge of the second year of high school, and he uses the law of Lopida.

I thought that if Sang You didn't understand, he would change his approach.

I didn't expect it to be quite unexpected.

When he packed up and was about to leave, Sang You smiled and said, "Senior, leave a contact information." ”

After a pause, Sang You hurriedly added: "I've troubled you many times, and I want to find an opportunity to invite you to a meal to express my gratitude, because I don't usually see it, so it's safer to leave a contact information." ”

-

Sang You's way back to the classroom was jumped.

Today is a milestone day, a big step forward in the crush journey!