This paper mainly introduces the basic structure and the function of each part of servomotor. At first, it talks about what is servomotor and where does it used for. Three parts are introduced in the article, the integration part, the addition part, and the feedback part. In each part, the article talks what the electronic components that are used in each part and how do these electronic components make the arithmetic come true. At last, the paper will discuss the advantage of the feedback part.

With the explosion of the MetaVerse concept and the burgeoning of VR (Virtual Reality) technology, VR has been applied in diverse scenarios，for example，social networking, games, education, online retail, house inspections, exhibition tours, training, virtual concerts and so on. Learning in the 3D environment of virtual reality can bring people an immersive interactive experience, which can improve the learners’ efficiency and deepen understanding. Music learning mainly includes the cultivation of rhythm (or sense of music, also including intonation), mainly relying on ears, followed by muscle memory, and the immersion of VR games is an optimal solution for music learning. This work proposes a VR-based drum learning game to solve several troubling problems such that when drummers practice real drums at home, the sound gets too loud, and the real drums occupy a large space, going out to practice drums will take much time. But to play drums in VR game, just put on a portable VR glass and pick up the touch controllers, drum players can practice at anytime, anywhere. What's more, it's very easy for novice to get started quickly. Another conspicuous advantage of VR is it provides an immersive experience for users，including a 360-degree panoramic screen, spatial audio, and authentic atmosphere.

Artificial intelligence has emerged with big data technologies in natural language processing and been applied to creative solutions for overload information especially around the time of the COVID-19 epidemic. This paper provides a comprehensive review of research dedicated to applications of artificial intelligence in misinformation detection. This work organizes the necessary background material for COVID-19-related misinformation detection in NLP, concentrating on the transfer learning technique. Database, data preparation, and modeling make up the major body of information. In the part of modeling, it will merge the attributes of the pre-trained model with the specifical task scenario to explain and present pertinent comments on the future model's improvement under the task scenario. This research will benefit the decision-making and information screen for people's inability to distinguish truth from fiction during the COVID-19 pandemic.

The Enigma machine is a kind of advanced mechanical encryption system used by the Nazi German military during World War II, with the rotor structure as the main structure. Cryptographic machines generally take the form of a boxed structure. When encrypting a string of characters, the user enters the information into a machine or system and gets ciphertext. The original information can be obtained by reverse operation of the ciphertext. As the operator enters the message to be encrypted, a sequence of plain-length passwords can be recorded based on the sequence of letters lit up on the lamp board. This article will focus on the simple structure of the Enigma machine and the mathematics behind it, thus illustrating its importance and security in the history of human encryption. Then, to further explore the working principle of the Enigma machine and help to better understand its internal nature, the essay has provided a simple code that can realize the simple function of the Enigma, and also shows a simply equipped Enigma machine.