Video Text:

The [ɑ:] sound. The jaw drops more on this sound than it does on any other vowel sound. Ah, ah. And as you can see, the tongue is laying there on the bottom of the mouth. Ah. So, the jaw drops here, make the sound, ah: pretty basic, simple, and straightforward.
发[ɑ:]这个音时，下巴比任何一个其他元音下移得更多。Ah, ah. 如你所见，舌头平放在口腔下部。Ah. 下巴移到这里来发这个音，ah。非常的基本、简单且明了。

Sample words:

father
父亲

collar
衣领

calm
平静的

Sample sentence:

The party at the bar was a mob scene.
酒吧里的那场派对挤满了乱糟糟的一堆人。