The love of functions and derivatives

Suddenly, the gates of the test center composed of parallelograms closed slowly, and the students swarmed out, looking for the two familiar faces of their parents among the crowded faces.This includes classmate C.

Classmate C was abused by this year's math papers. She usually has a level of about [-] points, and she can get up to [-] points with super long performance. Before the exam, she listened to the nonsense of her math teacher-"The college entrance examination The papers are simpler than the usual simulated papers."

So she stepped into the gate of a high school proudly with the wish to pass the 120 exam.As a result, she walked out of the test center like a drowned chicken.

Student C silently calculated the empty questions that he hadn't done, and then silently calculated the questions that he was not sure about. With a trembling hand, he almost threw the admission ticket on the ground.

Not far away, classmate C's mother is welcoming her child with an amiable smile like a leader condolences to the masses.

This is an extremely rare smile, as rare as the sun rising from the sky and raining at the same time - it's not impossible, it's just too rare.

You know, classmate C’s mother is usually short-tempered and likes to call the wind and rain, especially can’t understand classmate C playing with mobile phones in leisure places such as sofas, chairs, and beds. As long as classmate C is free, mother C will point fingers and say: Go dry my clothes."

Classmate C put down the phone in dismay, and heard a sentence from behind: "I'm so old and I need to talk about things!"

But at this moment, the corners of student C's mother turned up into a standard smile for taking ID photos, showing eight teeth, and said softly, "Daughter—"

Classmate C's mother swallowed back the phrase "how was the exam" that her daughter would usually ask after finishing the exam, and then said in a gentle and delicate voice, "go home."