For the N, keep the tongue nice and wide as it lifts for the sound, nnn, now.

对于 N， 当它抬起声音 nnn 时， 请保持舌头良好和宽阔。

When you think about it, the tongue position for the D, ddd, with the tongue tip up, is really similar to the N, nnn.

仔细想想，D, ddd 的舌位，舌尖向上，与 N, nnn 非常相似。