These are the five long monophthongs.

以下是五长。

First let's look at the twelve monophthongs.

首让我们看一下 12 。

A monophthong is a vowel in which the tongue stays in the same position.

是发时舌头保持相同位置的。

The qualities of diphthongs are not as same as monophthongs because of gliding.

由于滑，双的质与不同。