Happy times are always short-lived.

For the first time, Li Mu realized the meaning of this sentence in the process of learning.

From 6:40 a.m. to 8 a.m., when the library opened, he didn't seem to come back to his senses, and then when he entered the library, time passed like water.

Library - Canteen - Library - Canteen - Library - Dormitory.

That's what a day's trip is.

In Li Mu's perception, it seemed as if he had never had such a fast day in his life.

"Lao Li, you are really a bull."

Back in the dormitory, Zhang Lei and a few people surrounded Li Mu.

"How did you manage to read a book for a whole day?"

"Share the tricks, okay?"

The three of them saw it with their own eyes, and Li Mu never put down the book at all.

On the other hand, they didn't come to the library in the afternoon, and they didn't go back to the library until after dinner, and although they spent eight or nine hours in the library, they actually spent two or three hours in a daze or playing with their mobile phones.

Hearing their question, Li Mu touched his nose and said, "Just look at it like that, what's the trick or not." ”

"You can read a book like calculus?"

"Uh......" Li Mu asked suspiciously, "Don't you think reading books is a very happy thing?" ”

Zhang Lei, Xu Sheng, Chen Kaiming: "......"

"Dog, you've changed. ”

The three of them shook their heads, and scattered back to their seats.

They don't have a common language with dogs.

李牧淡定地笑了笑。

The dog hasn't changed, but his brain has changed.

……

Nothing was said all night.

The next day came as promised.

Of course, there is also the multivariate calculus exam.

Before the third class in the morning, more than 30 students in Class 1 of the Department of Physics were already sitting in the classroom, one by one.

"As I said last week, there will be a small test in this week's class to test how well you have learned during this time, which is also our practice, and it was the same when I taught you one-yuan calculus last semester."

"The grades are included in the usual grades, and we have three small exams this semester, including a mid-term exam, and the three scores add up to 75% of the usual grades, so everyone has to work hard."

讲台上，一个大概五十多岁的教授微笑地看着教室中的学生们，手上也正拿着一叠打印好的试卷。

This is the professor who teaches multivariate calculus in the first class of the physics department, named Lin Yao, who is a professor at the School of Mathematics of Shanghai Jiao Tong University, and because he also has a very in-depth study of physics, he became their mathematics teacher.

Hearing the professor's words, the students present all pretended to wail first.

Of course, although it is pretended, it is not pretended in their hearts.

Forget about the unary calculus, it was already last semester, but this semester's multivariate calculus really made them feel the fear of being dominated.

The solution to multivariate calculus problems is basically to simplify them to unary calculus first, and then use the method of unary calculus to solve them, so to speak, they are inherently one level higher at the level of complexity.

So just a few classes this semester have already made them feel like they want to die.

Not to mention the upcoming exams, which are sure to be another torture.

Of course, Lin Yao didn't care about the feelings of these students, and asked the class representative to come up with a smile and start distributing the test papers.

In the fourth row, on a seat against the wall, Li Mu took the test paper from the students in front of him, took one of them, and handed them to the students in the back row.

For this exam, compared to others, he can be said to be in no hurry at all.

This is the confidence that the computer in his mind gives him.

Unlike the people around him who immediately went to see the question first, he took out his pen without hurry, wrote the name of his class and student number first, and then looked at the topic.

First of all, look at the question type, five multiple-choice questions, five fill-in-the-blank questions, and four major questions.

The fill-in-the-blank questions are all five points, adding up to fifty points, four big questions, the first two are ten points, the last two are fifteen points, and the full score is 100 points.

And the time is also 100 minutes, two classes plus 10 minutes between classes.

The next step is to review the questions.

At this point, the computer in my mind was running at a rapid pace again.

When the information on all the topics entered Li Mu's thinking, the computer in his mind began to analyze these topics at the same time.

At the same time, the knowledge of multivariate calculus, which he had turned over twice in a day yesterday, also surged into his heart like a tide at this time.

It wasn't until about half a minute later that the corners of his mouth curled slightly.

Then I came to the conclusion that it was all pretty simple.

Even simple is a bit excessive.

This made him wonder, could it be because this was their first time taking the exam, and Professor Lin put a little water on them?

But he clearly remembered that the first small exam of one-yuan calculus last semester stumped the whole class?

The thoughts in his mind did not affect his analysis of the questions in the examination papers.

提起笔，就在第一道选择题的框中写上了【C】这个选项。

The answer to the first question has already been obtained in his analysis of the test paper just now.

Then comes the second question.

"Hmm...... ∂ f(x,y)/∂x and ∂f(x,y)/∂y are continuous for the function f(x,y) at the point (x0,y0) differentiable......"

"Obviously sufficient, choose A."

"Keep going."

With each stroke of the nib, one problem at a time is completed.

Even Li Mu doesn't need scratch paper anymore, because his mind computer is the best scratch paper.

不知道多久过去。

Unconsciously, Li Mu had already written the last question of the fourth question.

And because he had already deduced this question by multitasking when he was doing the previous question, he began to write it after he got it.

"Well, since ∂D is a compact set and u is continuous on ∂D, it can take a non-negative minimum value on ∂D and then ......"

"So the proposition is true."

"OK, done."

Putting down the pen in his hand, Li Mu didn't even check.

"There's no one who can't even do this kind of question, right? ”

He shook his head.

Belch...... Probably not, right?

I feel that the fifteen points of this last big question are like being given away for free, and the question is indeed interesting, but it is not too much.

There are still a lot of bulls in their class, he studied so seriously last semester, and his final grades didn't even get into the top ten.

Thinking in his heart, he also came back from his state of being in a state of consciousness.

But as he looked up at the time of the clock in the classroom, he froze.

Clams?

It's only been more than forty minutes?

"Jingle Bell~"

The bell rang suddenly after class, as if answering Li Mu-

That's right.

It's only been more than forty minutes.

Just one lesson!

Li Mu rubbed his face.

Good guys, this seems to be a bit ...... Quick?