HS code-driven customs clearance SLAs

List of the table of contents of this article:

• 1,HS code-driven customs clearance SLAs What is TT, IT, TN, (TN-C, TN-S, TN-C-S) system?
• 2, What is a language symbol system? What's the function?
• 3, What is a symbol system Unify
• 4, How to enter special symbols in Windows system?
• 5, What extracorporeal symbol systems have human beings have at present

What is TT, IT, TN, (TN-C, TN-S, TN-C-S) system?

1. TT-mode power supply system refers to a protection system that directly grounds the metal shell of electrical equipment, which is called protective grounding system, also known as TT system.

2. [Answer]: TN, TT and IT systems are the three grounding types in the low-voltage power distribution system respectively. In the TN system, the neutral point of the power supply is directly grounded, and the shell of the electrical equipment is connected to the connection point with a protection line. TN can be divided into three systems.

3. The TT system is a system in which the neutral point of the power supply is directly grounded and the shell of the electrical equipment is also directly grounded. Usually, the grounding of the neutral point of the power supply is called working grounding, and the grounding of the equipment shell is called protective grounding. In the TT system, these two groundings must be independent of each other.

4. Then this system is called TN-C system;If the N line in the system is all separated from the PE line, the system is called the TN-S system; if the N line and PE in the first part of the system are combined into the PEN line, and in the latter part of the line, the N line and the PE line are completely or partially separated. Then this system is called TN-C-S system.

5. The neutral point of the power supply of the TN system is directly grounded, and the neutral line is led out. According to its protective line form, the TN system is divided into three types: TN-C system, TN-S system and TN-C-S system.

6. TN system is divided into TN-C, TN-S and TN-C-S system. TN-C system: the protection line and the neutral line are combined into the PEN line. TN-S system: the protective line is separated from the neutral line. TN-C-S system: close to the power supply sideA section of protection line and neutral line are merged into a PEN line, which is divided into a protection line and a neutral line from a certain point.

What is a language symbol system? What's the function?

Language symbols are the tools for communication between people, and they are one of the most important communication media in human society.People use language symbols to express their thoughts, convey their feelings, and communicate their knowledge.

Various units in language are closely connected and depend on each other to form a system. Language can be divided into different hierarchical units, such as morphemes, words, phrases, sentences, etc. A language system is a hierarchical system composed of phonemes, morphes, words, phrases, sentences and other structural units.

The symbols of languages are not irreleverent, but interconnected and constrained, forming an organized and orderly strict system. It is generally believed that language is a layered device, which is operated by combination and replacement. In terms of its composition, the language symbol system is hierarchical.

What is a symbol system

1. Take the language of daily life as an example: symbols are "vocabulary", and the system is "grammar" (lexical and syntax). "Artistic language" also has "grammar", and people can do specialized research on it, such as music science in music.

2. Language uses a symbolic system to perform its communication function. Language symbols have their own characteristics compared with other symbols. These features are: linearity. Language symbols are sounds made one by one by the pronunciation organs.

3. Language is a symbolic system, a system that takes phonetics as the material shell and semantics as the content of meaning, and a system of lexical building materials and grammatical organization laws combined with phonetics. Language is a social phenomenon, the most important communication tool for human beings, a tool for thinking and transmitting information, and a carrier for human beings to preserve the results of understanding.

How to enter special symbols in Windows system?

1. The details are as follows: First, please turn on the computer, and then right-click the [Keyboard] button on the input method icon on the screen. The second step, next, we need to select the [Special Symbol] option on the screen.

2. Click the required special symbol in the right window of the special symbol to enter it. For example: ▓, ☆, ◤, ◥, etc. Then we click the punctuation mark on the left side of the window, and click the required punctuation mark in the right window of the punctuation mark to enter.

3. Here are several common methods: Use the combination key: Hold down the Alt key, enter a specific digital code on the numeric keyboard, and then release the Alt key to type the corresponding symbol.For example, hold down the Alt key and press 0169 on the numeric keyboard at the same time to type the copyright symbol.

4. The most convenient way to type special symbols on the computer is to use the soft keyboard of the input method.

5. The method of entering special characters is as follows: Use the symbol table: In the Windows system, you can press the Win+; key or Win+. The key opens the symbol table, selects the required symbol and copies and pastes to the required position.

What externalized symbol systems have human beings have at present

1. The externalized symbol systems that human beings have at present are as follows: Chinese system: Chinese is the most common language in the world, and it has A large number of Chinese character cultural elements and grammatical structures.English system: English is the most common language in the world, and it has many English vocabulary and grammatical structures.

2. Text. As the first set of externalized symbol systems mastered by human beings, the generation of words has also greatly accelerated the process of human use of externalized medium systems. Human morphological characteristics are more advanced than Homo erectus, and are divided into early Homo sapiens and late Homo sapiens.

3. Speaking was originally just a symbol that connects sound with surrounding things or the environment. In the social practice of human understanding and transforming the world, it gradually improved its abstraction ability and became a sound symbol system that can express complex meanings. At the same time, spoken language has also greatly promoted the development of human thinking ability.