Xin Zhai

Several people glanced at each other.Shi Jingchen looked at the row behind, but there was no one there.They excluded the four of them, and there were two people on the left and two on the right.

"Don't move, wait for them to pass." Shi Jingchen whispered.

In this case, after the teacher shouted in front, it is likely that no one responded.Some teachers will stop talking, some teachers will insist, and then the thin-skinned students will pass.For the first class, Shi Jingchen didn't even buy the textbooks, anyway he made up his mind to play dead later.

Ye Li was also worried at the moment.This feeling of fear is different from Shi Jingchen's, it's hard to describe.Originally, the two had shared the same bed, but this scene pushed Tong Yan back to the serious and serious position of the head teacher.On the first day of school, the scene of the class meeting in this classroom is vivid.

He raised his head and glanced secretly at Tong Yan, as if a primary school student saw his father invited by the teacher at school, he was the closest, but because of the wrong location, he was the most afraid.

"I'll say it again, the last row, sit in the front." Tong Yan said it again, this time slowly and calmly.Ye Li thought about it, how could he give up what he had decided on?

"Let's go." He patted Shi Jingchen who was sitting outside, and patted Su Xiaoqian on the other side.

Su Xiaoqian didn't care at all, and was the first to stand up.When Shi Jingchen saw this scene, he also had to stand up and follow behind with his head down.

The four of them walked under Tong Yan's nose and sat in a row clangingly.Shi Jingchen took out a pen and a notebook from his schoolbag, turned his head and whispered, "Lend me the book later."

Ye Li's current position is only one desk away from Tong Yan.He took out the book and put it on the table. Out of the corner of his eye, Tong Yan saw Tong Yan with one arm draped over the podium, his hand hanging down, holding a piece of chalk, and his fingers were stained white.

His eyes rested on his fingers for a while, and when he switched to another place, his mind began to wander.

Tong Yan's hand is very strong, and it will cause slight pain when pinching him in his pocket, and it is like a pliers when pinching him around his waist.The pads of the fingers are a little rough, and there will be obvious tactile sensations wherever they touch his body.So he decided to take a closer look next time to see if there were calluses or the like.

"Signals and systems are the basis of the entire control theory. Whether you continue to pursue this major or turn to popular electronics, hardware, and software, this course will be the most basic part."

Tong Yan made a simple opening remark, turned around and walked up to the podium, and opened his own book.

Many teachers in universities like to use computer projection to give lectures, and they talk about PPT one by one.Some say that they are speaking, but in fact they are basically reciting.The following students have learned to master later, and they don't need to bring any books, just print out the courseware.The teacher speaks at the top, and everyone just draws and draws in front of the courseware at the bottom.

"There is a transformation of the independent variable here. Let's take a look, page 12."

Ye Li was in a daze for a while, and when he came back to his senses, Tong Yan drew a waveform on the blackboard.

These things, when Tong Yan threw him a book when he was a freshman, he read it by himself, and didn't dare to ask if he didn't understand it.After getting to know him better, Ye Li would ask him questions when he was in a good mood.He found that Tong Yan was not familiar with many things, so he would look for relevant teaching materials and materials in front of him, and would not tell him to study it, and talk about it in a few days.

In short, what he learned from Tong Yan is not knowledge itself, but a learning method and attitude.

As he thought, he raised his head to look at the lecturer.Tong Yan is completely like a teacher at the moment, but it is different from other people's classes.

Tong Yan didn't prepare PPT in class because it was too troublesome.There are eight or nine editions of "Signals and Systems" in his bookcase.When he was in Australia, Ye Li also found three foreign editions for him. He originally wanted to buy them, but after looking at the price, they cost one or two hundred dollars each. Later, Ye Li took the trouble to scan them all for him.When it was sent back, Tong Yan gave a lecture, saying that this book is worth so much money, that the scanned version is not easy to use, and finally went online to say that he does not respect the author's labor.Ye Li thought it took me several days to scan a book, why don't you respect my labor?I was so angry with him that I ignored him for a month.

"The transformation of the signal below involves something about complex variable functions. Have you ever learned complex variable functions?"

Functions of complex variables are optional.The people below answered sparsely, some said "learned" and some said "no".

"If you haven't learned it, you can read it yourself. It's quite useful." Tong Yan muttered, and continued.

Before Ye Li returned to China, he finally bought those few textbooks for him.One is that he knows that Tong Yan likes it, or that he doesn't need many things, and this is one of them.The second is that he later agreed with Tong Yan's speech that books are sold too cheaply in China, and knowledge and copyright should be expensive.

He poked his head and looked forward, and after Tong Yan had completely entered the role of teacher, he began to observe him unscrupulously.

Tong Yan's clothes basically remain the same, but in fact, there are subtle differences in shirts and trousers, so subtle that you don't need to think about matching them, you can just wear a top and trousers.Shirts are changed every day, pants are changed every two days, and all clothes are sent to the laundry after a week.I like to use the simplest razor, and the faint aroma on my face is the smell of his shaving cream.

Ye Li's father passed away early, and Tong Yan was the first mature man he came into contact with.His way of thinking and living habits are different from those around him, which fascinates him.

Maybe Ye Li himself was sensible too early. Compared with boys and girls of the same age, he felt very childish and completely devoid of charm.

Before he knew it, Tong Yan wrote more than half of the blackboard, as if he was deriving some signal function.Halfway through writing, he turned around and asked, "So where is the high frequency?"

After finishing speaking, he suddenly looked at Ye Li.

Ye Li blinked, as if he had just woken up, he retracted the hand supporting his head.

he is asking me?

Tong Yan stepped off the podium, stood in front of Ye Li and Shi Jingchen, and said, "Where is the high frequency? Where is the low frequency?"

Ye Li lowered his head to look in the book. Shi Jingchen had just put away his phone, and the book between them was still on page 12.His heart was pounding, he looked up at the blackboard again, what was he talking about?

Ye Li flipped through the book quickly.

"odd multiples of ±π." Su Xiaoqian whispered across Pu Liang.

Ye Li heard what he said clearly, but he didn't dare to repeat it, he didn't even know anything about Tong's speech.

He turned the book from page 12 to page 18, but he still couldn't find the same thing as the last line on the blackboard.After turning two more pages, there was still nothing, Ye Li could only look up, looked at Tong Yan for help, and smiled embarrassedly.

Tong Yan frowned slightly, staring at him intently, without any intention of backing down.

Ye Li bit his lip, lowered his head, turned the book back to page 12, and read it carefully again.

The room was surprisingly quiet at the moment, everyone didn't know what happened, but Ye Li wasn't listening to the class?

Ye Li thought while reading the book, he is really scary!Don't talk about human feelings at all!

He turned a few more pages, simply looked up at the blackboard, calmed down, and thought about the last line of functions.

Discrete-time complex exponential, the last line has actually been derived.

"The high frequency is an odd multiple of the positive and negative pies, and the low frequency... is an even multiple of the pie." After Ye Li finished speaking, he dared not look him in the eye.

Tong Yan gave a half-smile, and said "Yes", took the book from the podium, looked down and said, "25 pages, a cycle of discrete time."

Ye Li then turned the book to page 25, and the conclusion he answered just now was right in the middle of that page, written in bold and bold!Ye Li thought, can't you just tell me "page 25"? !Is it fun to embarrass me?

Holding his breath, he listened to the rest without daring to miss a word.

As soon as the get out of class bell rang, several students surrounded him, and some asked him how the test scores were calculated, and the proportion of homework and experiments.Ye Li packed up his things, picked up his schoolbag and left the classroom.

"Hey, are you going back to the dormitory, Ye Li?" Pu Liang shouted from behind.

"I'll go and see my senior sister, you go first."

Ye Li ran to the fourth floor and pushed open the door of the laboratory. Lin Li was talking to another classmate on the computer.Ye Li then sat down beside him and waited. He saw that she was wearing a sweater and short skirt with light makeup on, and she was even more beautiful than before.

After Lin Li finished her work, she turned around and looked at him excitedly.

"Come back? Is it bad over there? Come back so soon?"

"It's okay," Ye Li said, "Senior Sister has become more beautiful!"

"Haha, you've changed too, you've grown taller."

"Really? I heard that you have a handsome guy as your boyfriend?"

"The news is quite good. Who did you hear it from?"

When the two met, they were very excited and chatted happily.Ye Li turned his back to the door, and heard footsteps at the door.

"It's winter, are you cold?"

Lin Li rolled her eyes at Tong Yan at the door: "You worry more than my mother." After speaking, she gloated at Ye Li.

Ye Li cursed inwardly, "You deserve it", and smiled at Lin Li, "Did Senior Sister run down the whole marathon last year?"

"Come down! It's a pity that you are not here, we will be together this year."

Tong Yan was bored, seeing that the two chatted without bringing him, he shook his head and went back to his office.

He sat in the room and vaguely listened to the chatter in the opposite room. He was very happy and chatted from ten o'clock to eleven o'clock.

At [-]:[-], he heard Lin Li say "Where to eat", and Ye Li said "Qinyuan".Lin Li asked softly again: "Just the two of us?"

"Well, I invite you alone." Then the two left chattering.

Up to now, although Ye Li is working as a tutor and going through the admission procedures, and hasn't seen each other in the past few days, he will always send him messages or call him, and report to him like a child.As a result, Ye Li ignored him all day except for meeting him in class.After dinner, Tong Yan thought, this guy won't be angry because of something in class, right?