The second harmonic is the one you get from the string vibrating in halves. Each half of the string vibrates at twice the frequency of the whole string. The 2:1 relationship between the pitches of the first and second harmonics is called an octave. (I know that the word suggests the number eight, not the number two. Don’t worry about it.) The pitch that’s an octave above middle C has a frequency of 2 Hz, and it is also called C. Both of these notes have the same letter name because in Western convention, notes an octave apart from each other are considered to be “the same note“. The important concept here is that you can move up an octave from any pitch by doubling its frequency. You can also move down an octave from any pitch by halving its frequency.
Россиянин год прослушивал квартиру бывшей возлюбленной и отделался условным сроком20:58。业内人士推荐新收录的资料作为进阶阅读
Models excel at code, but not at visual inspection. If there are visible differences (e.g. an small element is RED, but should be BLACK), a model will gleefully say that there are no differences, or that there are not important.，推荐阅读新收录的资料获取更多信息
is_even := n % 2 == 0; // COMPILE ERROR — mixed % and ==，推荐阅读新收录的资料获取更多信息