Sounds in unstressed syllables are frequently weakened, for instance by shortenings, elisions, etc. Because grammatical words (words that do not have a dictionary meaning in the way we normally expect nouns adj, and adverbs to have) are usually unstressed, their reduced or weak pronunciation are very frequent, even more than the strong form. But not all grammatical words have an alternation between weak and strong pronunciation. For instance, only monosyllabic grammatical words my have a weak form.Changes affecting grammatical words are systematic since they follow general language rules and properties of sounds. For instance, the more centralised a vowel. The weaker it is. The greatest weakening for any sound is the elision. (Garcia and Maidment)

Roach: Usually a speaker can be understood even if he is not using weak forms so why is it important? Firstly, because native speaker will find an 'all-strong-form' pronunciation unnatural and foreing-sounding, something that learner may want toavoid. Secondly, speakers who are not familiar with the use of weak forms are likely to have difficulty understanding speakers who do use weak forms.

VOWEL CHANGESWeakening makes all vowel move to the centre of the vowel space. They will first move to the central vowel quality nearest to their original one. When a vowel is already weak (as in 'could') it can stay unchaged or it may be further weakened to a schwa. CONSONANT CHANGESConsonant change are not an intrinsic part of weak forms but an optional in a scale of weakening which depends on the speech register that is used.

/h/ my be elided if it is not at the beginning of the utterance (following a potential pause)

/d/ /t/ may be elided when at the end of a word and preceded by another consontant.

The STRONG FORM is used in the following cases: (Roach)

1) when thy occur AT THE END of a sentence. Expect for: she; he; we; you; him; her: them; us, which do occur in weak forms in final position.

2) When a weak-form word is being CONTRASTED with another word. 'the letter from him, not to him'

3) CO-ORDINATED USE OF PREPOSITIONS: 'I travel to and from London' 'A work of and about literature'

4) When a weak-form word is given stress for the purpose of EMPHASIS. 'You must give me more money'

5) When a weak from word is being cited or quoted.'You shouldn't put 'and' at the end of a sentence.'

From Garcia y Maidment I chose other reasons why weak or strong should be used. (

1) in the following grammatical structures the strong forms will be used.'That's the picture I was looking at''you were later than I was this morning.'' He can sing well, bit I can too'

'She is more younger than I am'

The reason is that a word which normally follows the italic-word preposition or auxiliary verb has either been deleted or moved to some other position in the sentence, leaving the auxiliary or preposition behind. The auxiliary or preposition is said to be stranded.

An exception is when 'have' is immediately preceded by another auxiliary (can't, could etc). In this case the weak form will be used even though 'have' is stranded.

2) There are some word in which their use of the weak or strong form is determined by their function.

'her' 1) as possessive adjective /h/ is not dropped as in 'this is her car' 2) as personal pronoun a 'schwa' may be used as in ' it belongs to her'

Just /dʒʌst/ /dʒəs/ 1) 'only' or simply' as in 'I just told her the truth' WEAK 2) 'precisely' or 'exactly' as in 'I arrived just in time' is usually stressed so it's STRONG 3) 'A short time ago' or 'a shot time before' as in 'I've just seen him' it can be WEAK if unstressed or STRONG if stressed.

Some /sʌm/ /səm/ /sm/ STRONG 1) When it precedes countable singular nouns and it means 'a certain' in 'some animal was shot' 'some girl talked to me on the phone'2) when it precedes certain non-countable noun and means 'a considerable amount of' in 'I haven't seen you for some time' 3) When used as a pronoun as in 'Some boys ran' or 'I bought some'4) 'part of a whole' in which is usually stressed and strong, 'I met some (but not all) of the people at the party.

WEAK1) 'I need some money' /səm/

That //ðæt/ /ðət/

STRONG: Adjective or pronoun 'that boy is sad'

WEAK: relative pronoun or conjunction 'He's the man that I was talking about' (pronoun) 'I know that you have a bike' (conjunction)

There   /ðeə/   /ðə/

STRONG: Adverb 'I bought it there'

WEAK: as an existential construction 'There is'

3) Constructed negative forms

4) Possessive nouns such as yours, his, hers never used in weak forms5) Words such as: on, off, up out, round while (as grammatical words) do not have a

weak form.