They want to get as far away from each other possible, the ideal angle is 120. But what we have here is a four-membered ring, so what angle does 90° that have to be, that bond? 90 degrees.

它们想要尽量远离彼此，最理想的是形成120°键角,但现在是个四元环,所以这键角应该多大？

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If you allow a little bit of spacing, a little more space between your frequencies, they're a little bit farther apart, then you can move from closeness plays to spacing and you get the consonance.

如果让频率间有点间隔,给频率间多一点空间,让它们彼此远离一些,从密集的音高,转向有间距的音程,就能得到和谐音

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