回复：Bill, is this better?

i am picky here for your /chain/ pronounciation, hope you don't mind. You've already been very good now.

I am not sure why I am interested in the two sounds and cannot help digging more into them. Below you will find more of my explanation on the pronounciation of the sounds /ei/ and /i/, it may not right and comments are welcome.

I am a little exagerating in the explanation. comparatively speaking:

For the /chain/ sound:
1. two stair case; /ei + i/;
(here /ei/ is actually is not the sound for letter A, just use it here for easy demonstration)
2. for first /ei/ sound:
张嘴一厘米；嘴角后拉；
舌尖轻低下齿龈（或更下点）；
设后撤一点，舌前部向两侧铺开，并触及两侧下牙；
音的起始点在胸腔及咽喉部（不是在舌前部）；
3. for /i/ sound:
张嘴0.5厘米，舌前部向前，向上伸抬，嘴角稍微后拉；
舌前部向两侧铺开，并触及两侧下牙；；
音的起始点在胸腔及咽喉部（不是在舌前部）；

靠解释很难说的很清楚，发音位置也因人而异。