Good Morning vs Good Morning

[yangmuye]

Where did you get this idea?

If you are talking about “citations and references”, it's not an academic study but my feeling.

I realized the second point when I couldn't get my stress right in Portuguese. (I learned a little Portuguese for some reason)
The only distinction between a stressed syllable and a non-stressed syllable in Portuguese is the length of the vowel.

I got the first point because I'm memorizing words now.
I think vowels like /aɪ/ /eɪ/ /ɔː/ /aʊ/ /oʊ/ /(j)uː/ /iː/ /ɑː/ /æ/ /ɛ/ seldom appear in non-stressed syllable.
/ʌ//ə(r)//ɜr/ are completely complementary (In Am.Eng).
/ɪ/, if it's represented by the letter E, is usually pronounced /ɛ/ or /iː/ when it's stressed.

[5jj]

If you are talking about “citations and references”, it's not an academic study but my feeling.
I am afraid it's not a very helpful feeling.

The only distinction between a stressed syllable and a non-stressed syllable in Portuguese is the length of the vowel.
That is not the case in English

I think vowels like /aɪ/ /eɪ/ /ɔː/ /aʊ/ /oʊ/ /(j)uː/ /iː/ /ɑː/ /æ/ /ɛ/ seldom appear in a non-stressed syllable.
In a completely unstressed syllable, many vowels emerge as /ə/, but most vowels retain their quality when there is secondary stress.

/ɪ/, if it's represented by the letter E, is usually pronounced /ɛ/ or /iː/ when it's stressed.
Can you give some examples of this?.

5

[yangmuye]

I am afraid it's not a very helpful feeling.
That is not the case in English

Of course, they are useless for native speakers.
But I think it's helpful, at least for Chinese speakers to know that the length is more important than the pitch.
I understood patran's problem immediately because I had the same problem.

In a completely unstressed syllable, many vowels emerge as /ə/, but most vowels retain their quality when there is secondary stress.

Yes. But a secondary stress is also a stress.
Well, I admit that my diction is not good. If fact, there are many cases where the vowels are not stressed but retain full. You may give better counterexamples.

According to dictionary.com, the unstressed prefix a is usually a /ə/,

e.g. adjoin adject, assent, about...

But if the a is followed by consonants like /p//t//k/, it is usually a /æ/.

e.g. advance, advice, accede...

If a word has two syllables, and the second syllable has a consonant ending, it's usually non-reduced. But If the ending is /r/ or /n/, it's usually reduced.

Can you give some examples of this?.

It's not a absolute rule, either. Examples:

'record vs. re'cord
disreputable vs disrepute
compete vs. competent
comedy vs. comedian

# EDIT
It seems that I've said too much off-topic things.
I'm not advocating “Pitch hasn't nothing to do with stess.”, “Length is the only feature of stress” or “Unstressed syllables don't contain full vowels”.