I remember that the love letter I wrote to my sister at the time was not very high-level, and the words and sentences might be better than hers, but if you look at it from today's perspective, it would still look very naive.

rewrite it? As soon as this idea came to my mind, I couldn't help but reach out and pull out the pen in the pen holder.

I found a piece of yellowed A4 paper in the drawer, scratched my head after unfolding it, and decided to write a different love letter.

"Just use a mathematical definition of science to express it!"

After I made a decision, I buried my head in writing.

After finishing writing and putting away the pen, I stretched out my hand and flicked it on the paper lightly. After folding it, I got up satisfied and walked to my sister's room.

It is estimated that my sister must not understand, but this does not affect, I will explain it to her one by one.

Compared with my room, my sister's room is much warmer.

The wallpaper was pink, and it was covered with lollipops. The stuffed dolls hanging on the edge of the bookcase, especially the big bear on the bed, had a head that was half her size.

The quilt cover is light yellow with light blue flowers printed on the surface. The bed sheet and quilt cover should be of the same style, and the pillow looks like a pink heart.

I stood at the door and knocked gently on the door. My sister who was packing her clothes turned her head, and when she saw it was me, she was instantly happy.

"Brother, are you here to help me clean up?"

I held the piece of paper between my fingers and shook it at her,

"Send you a code letter?"

"Code letter?" My sister put the skirt in her hand on the bed in confusion, then walked up to me and took the letter between my fingers, "What code letter!"

"Open it and see if you can understand it?"

My sister curiously opened the letter and read it out in a low voice,

"For any c greater than 0, there is a large X greater than 0, and the absolute value of the small x is greater than the large X, then the absolute value of I (x) minus you is less than the small c."

"???" After reading it, my sister turned her head to look, her forehead was full of greetings.

"Don't understand?" I giggled and put my hand on her shoulder.

"No!" Sister shook her head honestly, "Can you explain?"

"Of course, it's actually very simple. Translating into Chinese is..."

I put my hands on my sister's pink shoulders, and gaze at her beautiful eyes dotingly and tenderly,

"Even if you give me the whole world, I will only be around you."

"Why is it translated like this?" My sister still looked at me in confusion, "I still can't understand!"

I sighed speechlessly,

"The original sentence is not important, the important thing is what it represents!"

"But..." Sister pouted, "I still want to know the principle of this translation."

"Oh! Sister, you really don't understand style!" As she said that, I grabbed her wrist and walked to the desk, "Come here, I'll give you a lesson on the definition of mathematical limits."

I took out a pen from the pen holder, then pulled out a piece of waste paper from the side, and read as I wrote,

"lim i(x) = you, x → infinity, you can understand i(x) as a function, x is the independent variable of the function, and 'you' is the limit value of the final i(x), that is , no matter which value x takes from negative infinity to positive infinity, I can only approach you in the end! Understand?"

My sister turned her head sideways and looked at me, her big watery eyes blinked hard.

"You want to tell me that no matter what happens in the past and in the future, you will always be by my side, right?"

"Bingo!" I smiled and gave my sister a thumbs up, "So, what about your promise?"

"My promise?" My sister turned her head away, with a cute smile on the corner of her mouth, "What kind of promise do you want?"

"As long as you give it, I want it!" I sat on the stool, gently hugged my sister's slender waist, and guided her to sit on my lap slowly.

"I don't have any promises!" After sitting down, my sister bowed her head and said with a pretty blushing face, "I only have..."

Without saying a word, she reached out to hold my cheek and kissed my lips lightly,

"Is this ok?"

"This is the best!"

After I reached out and tapped the tip of her small round nose, I smiled with satisfaction.

After speaking some unbearable nonsense to my sister, I got up and went back to my room.

I didn't have much to pack in my room, and it took about half an hour after returning to put the unnecessary ones and the ones that could be donated into two large cardboard boxes.

Then I squeezed the rag again, and wiped the desk, the bookshelf, and some dead spots on the bedside that I didn't pay much attention to on weekdays.

Feeling almost the same, I ran to my sister's room again.

She was still packing the wardrobe at this time, the main reason was that she had too many clothes, but she was very confused about which ones could be discarded.

"With ink like you, don't even think about cleaning it up in one day!"

I sat on her bed, looking at the pile of clothes, speechless.

"What can I do, I'm also very uncomfortable!" My sister held a white princess dress in her hand, gestured in front of her, then turned to me, "Brother, do you think this dress looks good? "

"You bought this when you were fifteen years old. Do you still wear it now?"

"But this is my first princess dress, it's very memorable."

"No, your first princess dress was the one your mother bought for you when you were three years old."

"But that one is no longer there, so this one has become my first one."

"Oh, it's alright, alright!" I waved my hands speechlessly, "You can organize your clothes yourself, and I'll help you clean up the rest."

"Brother, you are so kind!" My sister jumped over and kissed my side cheek with her small mouth, "Now I can slowly tangle over those needs and those that are not needed!"

Okay, I help her clean up, and co-authoring is just helping her expand more tangled time.

My sister's room is also quite neat. There is only one pen in the pen holder on the desk. I took it from me when I said that I wanted to keep writing a diary a few years ago.

As for the desktop computer, the plastic bag of the keyboard has not been removed yet.

On the middle three floors of the bookcase are all the textbooks from kindergarten to high school graduation, and the extracurricular readings seem to have a hardcover version of "Hua Xuyin" and a complete set of "Dumb House" in black.

Oh yes, there is also a copy of Marquez's "One Hundred Years of Solitude".

This book was taken from my bookshelf during the summer vacation this year. I remember that she suddenly said that she wanted to read a world famous book, and then she took a copy on my bookshelf.

However, looking at the location of the bookmark, she probably just flipped it over when she picked it up, and then she was on the side and never touched it again.

I'm really helpless. In my opinion, as long as you calm down, there is no book you can't read, but I don't know why when my sister sees something like "One Hundred Years of Solitude", "Notre Dame de Paris" and "La Traviata" Such a book, calling it such a headache?

Wouldn't she have a headache when she watched "Hua Xuyin" and "Dumb She"?

To put it bluntly, it is still a question of interest!