后元音：[ɑ:] [ɔ] [ɔ:] [u] [u:]
后元音发音要领：①舌尖不触下齿,舌身后缩,舌后部向软颚抬起,除[ɑ:]外,双唇要收圆.
②发[ɑ:][ɔ:][u:]时要注意长度,不要发得太短.
[ɑ:] 舌尖不触下齿,口张大,舌身平放后缩.
Art army star father garden tomato a large car,half a jar,after the bath
I like to pass through the garden park.
Far from eye,far from heart.
[ɔ] ①舌尖不触下齿,口张大,舌身尽量降低并后缩.②双唇稍稍收圆.③可先发[ɑ:],然后将舌身再稍稍向后缩,双唇稍稍收圆（不要突出）即可发出[ɔ].
On off hot want doctor foreign cotton socks,borrow a clock,a pocket watch
The coffee is top quality.
When the shop was robbed,everybody was shocked.
[ɔ:] ①舌后部比发[ɔ]时抬得略高.②双唇也收得更圆更小,并须用力向前突出.
Always or law before caused daughter all in all,more and more,a short story
Paul’s four and can walk and talk.
The storm draws near---we ought to go indoors.
[u] ①舌尖不触下齿,舌后部向软颚抬起,舌身后缩.②双唇收圆,稍向前突出.
Full look wood foot woman sugar push and pull,good books,by hook or by crook
The cook cooks good food.
The woman stood for as long as she could.
[u:] 双唇比发[u]时收得更圆更小,向前突出,舌后部比发[u]时抬得更高.
To who lose group music fruit a blue balloon,an afternoon in June,huge rooms
The news is too good to be true.
That rule is useful once in a blue moon.