and /o/ can occur at the beginning, middle, and end of words in English. The following are some of the allophonic variations of /k/ and /b/ Allophonic variations of /k/: Allophone Occurrence Example [kH Aspirated release in word initial and stressed positions keep [k-1 Unreleased in word final position take k Unaspirated release in consonant cluster, esp. with/s/ sk k:] Lengthening, when an arresting /k/is followed by a releasing /k/ take K im k Nasal release, before a syllabic nasal kI1 Bilateral release with /1/ clock [c]or [ k] Assimilated to a front sound keen Glottal stop, before syllabic [n] aco Rounded before a rounded sound Allophonic variations of /b/: Allophone Occurrence Example [y Unreleased in word final position and some clusters flag L: I Lengthening, when an arresting / is followed by a releasing /y/ big grapes 1] Bilateral release before/V/ Nasal release, before a syllabic nasal pig and goat []or [x Assimilated to a fronted sound Rounded. before a rounded sound goose Pronunciation difficulties The English stops do not generally cause an intelligibility problem among the hinese EFL learners but some learners may devoice final position voiced stops so that tab may be pronounced as tap, code as coat and Ai: b/ as /i: k/. Lengthening the vowel before the voiced stops will aid in the perception of a voiced final stop. /i need, for example, is usually a little bit longer than /i: / in neat when they are in similar phonetic contexts. Another difficulty with the Chinese eFl learners is the pronunciation of the stops in consonant clusters. Drill the sounds in all positions paying close attention to the strength of production and the degree of voicing 辅音:塞音 在这一单元,我们将学习英语的爆破音,也叫塞音。and // can occur at the beginning, middle, and end of words in English. The following are some of the allophonic variations of /k/ and //: Allophonic variations of /k/: Allophone Occurrence Example [k] Aspirated release in word initial and stressed positions keep [k-] Unreleased in word final position take [k] Unaspirated release in consonant cluster, esp. with /s/ sky [k:] Lengthening, when an arresting /k/ is followed by a releasing /k/ take Kim [k(] Nasal release, before a syllabic nasal beacon [ kl ] Bilateral release with /l/ clock [c] or [k] Assimilated to a front sound keen [] Glottal stop, before syllabic [n] bacon [k] Rounded, before a rounded sound quarter Allophonic variations of //: Allophone Occurrence Example [-] Unreleased in word final position and some clusters flag [:] Lengthening, when an arresting // is followed by a releasing // big grapes [l ] Bilateral release before /l/ glad [(] Nasal release, before a syllabic nasal pig and goat [] or [] Assimilated to a fronted sound geese [] Rounded, before a rounded sound goose Pronunciation difficulties The English stops do not generally cause an intelligibility problem among the Chinese EFL learners but some learners may devoice final position voiced stops so that tab may be pronounced as tap, code as coat and /li:/ as /li:k/. Lengthening the vowel before the voiced stops will aid in the perception of a voiced final stop. /i:/ in need, for example, is usually a little bit longer than /i:/ in neat when they are in similar phonetic contexts. Another difficulty with the Chinese EFL learners is the pronunciation of the stops in consonant clusters. Drill the sounds in all positions, paying close attention to the strength of production and the degree of voicing. 辅音: 塞音 在这一单元，我们将学习英语的爆破音，也叫塞音