The [ ？] sound is a front vowel， which for me means it feels like
it comes more from here ， aa ， than from here ， ah. It's a bit difficult
to explain， so I am going to explain it in terms of another vowel， and
that is the [e] as in "pet" vowel. Both of them ， eh ， aa ， you can
see my tongue is up ， as opposed to ah ， "father" ， where you can see
the dark space in my mouth. Aa， all you see is tongue. So it's coming
up， and making a bit of a wall ， so that you see this part. The way
it's different from the eh vowel， which is more like this， eh ， aa ，
is that the tip of the tongue is not touching underneath the teeth as
it is in eh. This part of the tongue is a little more vertical and more
spread for me ， which feels like it creates more space back here. Aa ，
aa. Also the jaw has dropped a little bit more than on eh. Aa ， aa. And
the last subtle change that happens is here. It's easy to see. The lip
comes up just a little bit. Pets， pats.

    [ ？] 是一個前元音，它和[e] 音的共同特點是發(fā)音時舌頭要抬起，這和發(fā)
father中的[a：] 音不同。發(fā)[a：] 音時可以看見口腔中的黑影部分，但是發(fā)[ ？

    ] 時只能看見舌頭。因為舌頭抬起形成了一座“墻”。

    [ ？] 與[e] 不同之處在于：發(fā)[e] 時舌尖觸及下面的牙齒，但是發(fā)[ ？]
時并不觸及；發(fā)[ ？] 時舌根部分更加垂直、更加舒展，感覺在后部制造出了更
多空間；另外發(fā)[ ？] 時下巴下移的位置要比發(fā)[e] 時更多一點，而上嘴唇則要
比發(fā)[e] 時上移得更多。

    Sample words：

    habit 習(xí)慣

    understand理解

    Sample sentence ：

    Cameron is mad about fashion. 卡梅隆癡迷于時尚。