知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。 "Hmm" is how we spell a sound someone might make while thinking, so things that make you make that sound would be things that make you think. (There's no standard number of [m]s to write, as long as it's more than one. Follow along with the video https://alexisemsaf.eedblog.com/33864527/beat-can-be-spaß-für-jedermann