Dear principals and teachers: Recently, I found more and more garbage in the campus. Sometimes the garbage on the roadside and the roadside is garbage. In addition, some students do not pay attention to the hygiene.
The whole campus looks very untidy when they throw up waste paper and broken bags. Beside the garbage can, there are mountains of garbage and swarms of flies buzzing around. It's really sad for our whole school The overall image of the garden has caused a great impact.
Therefore, I suggest that the roadside garbage provided by schools and other places have some shapes, and it is better to classify the garbage, because I found that the garbage can be divided into "recyclable" and "non recyclable". On the one hand, it can increase the income of energy saving; on the other hand, students should establish the concept of resource saving. Only in this way can we The number of students in the school, the number of children in recess activities, a large number of carbon dioxide emissions rebound, only trees can enter the oxygen, the amount of carbon dioxide in the air can be purified, so we should plant more trees, so that we can have a better campus environment.
Dear principal, please take my advice, let the students take action, let us (1) more beautiful earth.
Students, do you know why airplanes fly in the sky? Do you know how to call a person who is far away from each other? You don't know why computers can meet people all over the world through the Internet. If you want to know the answer, just look at the book "100000 whys", which is very rich in content and interesting in knowledge, including knowledge of science, geography, history, etc It's not long to know it, but it's also equipped with a colorful image, that is, vivid and vivid. Let me give you a brief introduction to "what's the principle of the telephone".
The first telephone was invented by American inventor bell in Edison. In order to make it simpler, the basic principle of the telephone is to use electromagnet to turn sound into electric current, Then, the sound is sent to the receiver receiving the voice through the current transmitter. There is a thin diaphragm microphone, which can be converted into pulse voice.
It is transmitted to the receiver through the wire. The receiver is also a piece of film. The electric pulse from the other side can make the diaphragm vibrate and produce vibration.
The vibration through the sound wave is almost the same as that of the other side. This is what we hear The principle of the telephone is like this. It's not easy to understand.
Since the invention of the telephone for many years, the function and performance of the telephone have become more and more perfect. It has a profound impact on people's life and brought a lot of convenience to people. Students, if you want to know more about extra-curricular knowledge, look at this book.
It's not only There are scientific principles and the mysteries of nature. I think the content of this book will be very attractive to you.
Dear Mr. or MadamI IM, a senior in Computer Science Department of Peking University, I must write to you to state my inquiry / complaint / Invitation / request / suggestion. First of all, there are several factors that can explain the problem / complaint / Invitation / request / suggestion.
First of all, thank you for your attention and attention to this letter. If you can reply to this letter at your earliest convenience, we will not Thank you very much for your sincere Li Ming////////.