Letter to my daughter 185 will blossom without any seeds-learn to wait for the flowers to bloom.

Hello, baby girl!

Your key words: let grandpa pick you up again, happy to see your playmates again, play with toys and read books.

Brother keywords: Listen to the Romance of the Three Kingdoms, finish your homework, read the book and have a box, and complete Captain America.

Dad Keywords: time sponge loosens again, habits become empty, feelings about the broken bridge case, four people running in Jeffery Ji, sorting out morning reading materials, moving reading notes forward, why are we not dead, the future school.

Yesterday afternoon, my father got a call from my mother, saying that you were going to grandma's house. At the beginning, my mother didn't agree, so you started crying to see if you could go home and see you off. Dad's first reaction was that he couldn't go back, and he thought it would take too long to walk back without cycling. Later, I calculated the time, and I could get home in 20 minutes at most, so I was ready to drive back.

In the meantime, grandpa has received a phone call from his mother and rode to pick you up, but he didn't hear from his father.

Dad saw strawberries selling well outside the fruit shop on the road, so he bought a box of 2 kg. When we come to the steps of Building 8, we will see you standing in front of Grandpa, who is putting things in front of the motorcycle.

Dad went downstairs and handed you the strawberries to see if you could take them away. You shook your head and said nothing. Grandpa said that he kept strawberries for my brother and asked my dad where he bought them. Dad told grandpa that he bought it at the Love You Orchard in the southeast corner of the turntable. Grandpa said he would go up and buy you something to eat at grandma's later.

Dad stood in front of the building, holding the door in one hand, waving to you in the other, saying goodbye to you, and watching you leave slowly and go far behind grandpa's motorcycle.

Sadness always comes with parting, whether it's someone close to you or something close to you.

Fortunately, mom and dad learned that it was the two little girls in the neighbor's house behind that attracted you to grandma's house. For children, playmates are the most important, followed by toys. It is especially important for you to have your own playmates.

In this high-rise residential structure, every household has children, but there is little contact between them, which is an insurmountable obstacle in your childhood journey of finding yourself.

Dad wishes you and your two children a happy stay at grandma's house and adds more connections to the interpersonal network in your brain.

Dad finished writing the letter yesterday morning and made some aurora words. After finishing these two contents every day, I feel that there is really plenty of time left.

I remember that after I started writing to you last September, time was particularly tight every day. For a time, I was actually very nervous, afraid that I could not finish the project I had to do every day.

After nearly 200 days of persistence, my father has become more and more handy in writing letters and has become more and more accurate in grasping time. This makes dad feel that time is getting looser and looser recently.

When I was in junior high school, I first heard the saying that time is compared to water in a sponge. It is said that time is like water in a sponge, which has been squeezed. The reason is easy to understand, but it takes a long time to really become an idea you insist on every day.

No seed in the world can blossom after being planted. It needs cultivation, watering and fertilization to gradually take root, sprout, grow, mature and blossom.

We just need to do things step by step according to the procedure, and leave the rest to time. When time is needed, it will be fine naturally.

This is to remind mom and dad to try not to be anxious, dry and anxious on your way to growth. Love is dribs and drabs, love is concrete, not focusing on hopes and goals. Your feelings under various experiences should be the focus of your parents' attention.

Fortunately, writing to you two every day can remind you to make fewer mistakes every day.

Two nights ago, we fell asleep, you and your brother fell asleep, and dad slept soundly. Suddenly, my mother pushed my father a few times and said, there are many people under our window. Let's see what happened. Dad didn't respond. Mom went back to sleep and didn't want to take care of these things.

The next day, when my father went out, my mother met my grandmother across the hall and asked about the night before. Only then did I know that Uncle Duimen brushed a passerby after drinking and driving, and was called the police. The traffic police came, towed the car away, and people were taken away.

The uncle opposite earns a lot of money in key positions in the coal mine, but drinks almost every day. My son is about to take the senior high school entrance examination, and only my grandfather comes to pick me up and jump rope every day. Dad believes that it is useless to earn more if such a father is not on the job.

Maybe he didn't find the meaning of life, or maybe we don't understand other people's values.

Cases around us always make it easier for us to combine theory with practice, because people are more willing to pay attention to things around them.

This morning, four dads ran 13 km to the greenway. Wearing short sleeves, long sleeves, long sleeves and short sleeves, underwear and coat in turn, spring, summer, autumn and winter, the same environment, different people feel different.

Dad is very grateful to these brothers who can keep running together.

When I got home, my father read some sentences in parents' code and children's language in the morning, and felt it necessary to sort out the contents of the morning reading. More importantly, extract the key contents of every book you have heard and read. Although I thought it was important before, I didn't persist.

Next, dad will enhance the importance of morning reading and reading notes.

Today, I want to extract some information about immunity from Why Are We Not Dead that I heard yesterday.

The "innate immune system" is like an automatic defense mechanism, like a preset program. Once the enemy is identified, it will send out a danger signal, and then use the preset method to destroy the intruder. From the pathogen's point of view, it's simply an inferno. This process can be divided into two steps: identification and attack.

If the pathogen is bacteria, after the innate immune system recognizes it, it will carry out a series of signal transmission between molecules until each link mutually confirms that the infection is happening and determines the infection location, and various cells and molecules will come to fight from all directions. For example, some protein will stick to the surface of bacteria and mark phagocytes that specialize in hunting bacteria; Phagocytes will come and devour the whole bacteria, and then decompose them with chemical weapons. Of course, the immune system has many other strategies against the enemy, which one depends on the preset program.

If the pathogen is a virus, it will invade the inside of human cells. At this time, infected cells will choose to commit suicide. The human body depends on the trust between cells to function normally. Once the cell is infected or damaged beyond repair, the body will expect it to send a signal to inform the immune system in a specific way: help, help, I am infected, please kill me at once! Immune cells will come to kill infected cells. At this time, uninfected cells will also be vigilant and prepared to prevent themselves from being recruited.

The "adaptive immune system" is the body's last line of defense. If the innate immune system is the standing army of the body, the adaptive immune system is the special force, which specializes in dealing with emergencies and high-risk events.

The adaptive immune system mainly acts on two kinds of lymphocytes, B cells and T cells. There is a clear division of labor between them. B cells are responsible for secreting antibodies, that is, macromolecular protein, which specifically resists certain pathogens. You can think of B cells as a strategic force of heavy weapons. On the other hand, T cells are more like army troops, responsible for killing and all other work.

When the innate immune system is fighting, the adaptive immune system has received the signal and entered the alert state. A specific cell (antigen presenting cell) will send the information of pathogen to the adaptive immune system for analysis, and in case it needs to be dispatched, it can attack accurately.

The information of pathogens sent by cells is called antigens. The concept of antigen is more important. Let me explain a little here. Antigen refers to various foreign substances that can activate the adaptive immune system, including not only pathogens, but also inanimate substances such as pollen. We can imagine the process of adaptive immune system recognizing antigens as a person holding countless different keys, trying to see which key can open a specific lock in front of him. T cell is the key, antigen is the lock. Each T cell has a unique receptor molecule, that is, a substance that specifically recognizes antigens. Like every key, it can only open a specific lock. Once the antigen matches the T cell receptor, the adaptive immune system will be activated.

This is the "immune response". In the process of immune response, T cells will transform themselves into special forces (effector T cells), and then quickly replicate themselves to produce a special force to fight. Next, the copied T cells will further form a division of labor, some are responsible for killing pathogens, some are responsible for guiding work, some are responsible for avoiding losing control, and some are responsible for remembering to prepare for the next infection.

At the same time, stronger B cells will be stimulated by antigens and secrete antibodies, which is the ultimate weapon of the immune system. This process is amazing. B cells will quickly and randomly rearrange their genes to produce a series of mature cells, which will secrete different antibodies. Then, T cells will screen more effective B cells for replication. The author says that the process of random gene rearrangement in B cells is disordered, but the whole process is strictly regulated, which is simply a small evolution in the body. After that, the antibodies secreted by B cells will reach the infected place through the blood. You can think of antibody as a precision guided missile, which will block the activity of pathogens and eventually destroy them.

With the concerted efforts of Qi Xin, T cells and B cells finally succeeded in eliminating pathogens. However, it is very expensive for the body to start the adaptive immune system. When the war is won, these T cells and B cells mobilized for the war will also start programmed suicide, leaving only wooden memory cells. If this pathogen invades again, the adaptive immune system can recognize this pathogen more easily and prevent it more effectively. This is the principle of vaccine: immune memory is formed by controlled exposure to pathogens.

Several important knowledge points of immunization mentioned above are put here for us to learn.

I went out for joint inspection in the morning, but I finished this letter in a reasonable way in sporadic time.

Love, Dad.

2020.03. 12