Today, the chemistry teacher started to talk about the exercises at the back of the book again.

The chemistry teacher is a male teacher, of medium stature, and he looks quite energetic; A pair of silver-framed glasses are placed on the bridge of the square face, a wide forehead, and a pair of silver-framed glasses, and a yellow face with edges and corners, like a stone carving, giving people a very majestic feeling. He often wears his clothes, although they look a little old, they are very neat, and the whole person is very decent. But don't look at the feeling he gives people like this, but the words he says are terrifying, doesn't he coldly glance under the podium, "There are five exercises, and that one can't be done?" ”

"First ......," the students below whispered.

When the chemistry teacher heard this, his eyebrows were furrowed, his face was hideous, his face twitched, and he scolded casually and loudly: "I can't do the first question?" Did you listen carefully in class, so who said you wouldn't raise your hand! ”

The class was quiet, no one dared to raise their hands, and most of the students couldn't lower their heads any more.

The chemistry teacher breathed a sigh of relief, "I've passed this question, what other question can't be done?" ”

A weak classmate said, "The second question ......"

"What! The second way is no, what am I talking about, you haven't listened to it for a long time, haven't you? I have talked about the order of the solubility of common gases from large to small several times, okay, Yuan Nan, stand up and tell you about the order of the solubility of common gases from large to small.

Yuan Nan was about to lower her head to the table, and she could still let the chemistry teacher catch her, this teacher was simply amazing, she stood up timidly, and whispered: "The order from largest to smallest is NH3, HCl, SO2, H2S, Cl2, CO2."

The chemistry teacher's face finally softened a little, "Okay, this question has passed, Yuan Nan in your class will know, you won't, embarrassed to say it in the past, let me tell you, you are such a big person, you have to be conscious in class, if you don't know this question again, you will go out and think about the past." "There was another roar, and no one in the class dared to speak anymore when they heard this."

"Do you still know how to do that question?"

"No, the following will be done." The classmates said.

"It's going to do, okay, the girl in the second row near the window said the colored gas in the ABCD."

The girl with the black eyes stood up and said, "F2 in option A is pale yellow-green, Cl2 is yellow-green, Br2 in option B is reddish-brown, and I2(g) in option D is purple-red and NO2 is pale red gas, so the answer is C."

The chemistry teacher stared at the black eyes seriously, with a posture of hating iron but not steel, "You tell me again, NO2 is a light red gas, how many times have I told you, it is reddish brown, why can't you remember?" ”

“……”

"As a classmate in the top class, I can't even remember this, are you embarrassed? I told you, these are the basics, why don't you listen to them well! Only by memorizing the knowledge points can you do the right questions, why, you don't believe what I say, do you? Angry to the depths, the chemistry teacher threw the book directly to the ground, slapped the table suddenly, and the scolding suddenly resounded in the ears of every student, startling Cao Yu, who was sleeping low.

"Just five questions, you don't even know how to do the most basic, and there are people who remember the knowledge points wrongly, what's wrong with you, you're so ambitious, aren't you, don't you want to fly if you don't go back to walking, don't you?"

The silence in the "......" class was terrifying, and suddenly there was a "squeak", and the front door of the class was opened.