Why is it always swollen when you wear it back?

Yu Fei, who had been cramming for math for a day, was still dizzy when he woke up the next morning, and he still kept talking about the laws he summed up yesterday.

"The intersection is downward, the intersection is upward, the intersection is downward, the intersection is upward, the intersection is downward... Later, which side is it driving? The one with the bar?" He thought for a long time but couldn't figure it out. Started to flip the book again.

For Yu Fei, who barely passed the math test, it was already a great thing to make up for the monotony in one day. After all, Liu Ma is not a professional teacher, and it is already very good to be able to speak clearly, so he reluctantly memorized a formula , At most, I can write some basic exercises, but I can't write others.

Forget it, anyway, Wang Xu should only call this time, why bother so much?Thinking of this in his heart, Yu Fei took out his math book, wanting to familiarize himself with it before the first class, so as not to be sent back to the previous one.

Coincidentally, his math book was seen by Wu Yu who came to supervise.

"Read English early, read English." Wu Yu didn't say anything else, just knocked on Yufei's desk.

Yu Fei obediently put away the math book, and took it out again as soon as Wu Yu left.His deskmate Yang Da rolled his eyes again.

What kind of mathematics do you write in your self-study early, crazy ==

"Recently, Yufei's performance has improved a lot. I saw him writing in his math exercise book this morning." Wu Yu talked to Wang Xu, a math teacher next to him, and said, "Although it's not right to learn English from self-study early in the morning. , but it can also be seen that he really intends to study hard." It's better than sleeping before.

"Oh? Yufei was studying mathematics early in the morning?" Wang Xu stopped the pen in his hand, apparently interested in Yufei's early morning writing of mathematics, "Then I will test him hard."