The F.T.C.says children are important for three reasons.

VOA: special.2010.06.04

These between B and C and E and F didn't get filled in because they were already just the smallest amount that they wanted to deal with, just half steps.

但是B和C,E和F之间并没有被填上,因为它们之间已经是最小的距离,只是个半音级,人们愿意摆弄的最小距离

耶鲁公开课 - 聆听音乐课程节选

We can't go C, D, D-sharp, F.

不能是C,D,升D,F

耶鲁公开课 - 聆听音乐课程节选