High speed refers to advanced speed, compared with medium speed and low speed. In the environment where low speed is dominant, low speed is normal speed or constant speed, and in the environment where medium speed is dominant, medium speed is normal speed or constant speed.
The relationship between high speed and fast speed: the generalized fast speed (the comparison between fast speed and slow speed) in dichotomy includes high speed relative to slow speed, but the word fast does not mean high end. In multi-object comparison, fast speed is higher than low speed, lower than high speed and quasi-high speed. In dichotomy, fast is called medium speed, which is higher than normal speed and lower than high speed. In dichotomy, expressway is lower than expressway, express railway is lower than high-speed railway, and express train is lower than high-speed train.
The relationship between high speed and fast speed: the generalized fast speed (the comparison between fast speed and slow speed) in dichotomy includes high speed relative to slow speed, but the word fast does not mean high end. In multi-object comparison, fast speed is higher than low speed, lower than high speed and quasi-high speed. In dichotomy, fast is called medium speed, which is higher than normal speed and lower than high speed. In dichotomy, expressway is lower than expressway, expressway is lower than expressway, express railway is lower than high-speed railway and express train is lower than high-speed train.
Fast is compared with slow and constant speed (usually slow in technical system), and downward comparison means that two objects are comparing, and fast does not mean high end; High is the positioning of high-end, compared with middle and low, it is the comparison of three objects; If we compare the medium and low speed (constant speed) objects, in the velocity field, the medium speed is fast and the low speed is slow, which is faster than the low speed (constant speed). Therefore, in the dichotomy, the medium speed is called fast, so in terms of specifications, fast is lower than high speed.
In addition, in the eight-speed railway method of international academic circles, there are many comparison objects, and the fast speed is lower than the quasi-high speed and high speed. A similar example of the change of different status of the comparison object: a singer with a good voice is a good singer and a master in a small country, but emigrating to a big country may be an ordinary singer's level, which may be a poor level in the global comparison.