又聽了一遍，以下幾個發音我認為再下下功夫就好了

Mentally,"en"
Un-happy, "un", you sounded like "an"
Often
Alter,"al"
outcome
along; "long",
expect: "e",
value: "a"
productive
menu" "e",

總之，我覺得元音是一個單詞主幹，一定要發準，發充分，。你發“e"時嘴容易張得太大，而發“a"時又顯得不夠大。還有就是“l"音，跟在元音之後時，雖然發音不必太重，但舌位一定要到位，否則聽上去韻味不夠，比如“all", "wall" 等等。寫得匆忙，不周之處，望海涵。