s发/s/的读音规则一、s在词首时，除了sugar，sure以及sh组合发/ʃ/以外，其余一般发/s/ 例：surface，serve，seven，six，some，sign比较：design/di'zain/一般前缀，合成词不影响其读音s仍读成/s/例：unsafe，unsatisfactory，roadside，teaspoon，snowstorm二、两个s在词尾时读作/s/ 例：grass，glass，address，press，success，pass，miss，stress，across，swiss, progress，process，kiss三、词尾s在u后读作/s/ 例：bus，us，minus，abacus，plus，status，virus四、在sis组合的弱读中，两个s都读作/s/ 例：emphasis，analysis，thesis，crisisemphasise, emphasize, analyse/ analyze, criticise/criticize (criticism n.)五、s在字母c前常读作/s/ 例：muscle，discipline，science六、s在某些前后缀中读作/s/。
1．在前缀mis-，dis-中，s读作/s/ 例：mismanage，misjudge， misbelieve，disorder，disobey2．在后缀－sive，sity，－self，-some，-sy中，s读作/s/ 例：expensive，intensive，decisive, yourself，handsome，troublesome，tiresome，quarrelsome七、s在清辅音前后常读作/s/1．s在清辅音前常读作/s/ 例：honest，newspaper，task，satisfy，grasp (grab, grip)2．s在清辅音后常读作/s/ 例：sportsman，works，stops，roofs．八、词尾se在字母r，l，n后读作/s/ 例：horse，nurse，worse，course， universe，pulse，else，tense，senseI couldn't find good references by Googling, and I don't know anything about British English. As I think it through, it is quite complicated! Sorry -- we should really get around to some spelling reform. I hope others can help edit this list if they think of exceptions. In American English, typically· If there are any prefixes or suffixes causing an s to be in the middle of a word (either because the "s" is part of the prefix or because it is part of the root"), the "s" is always unvoiced清音/s/, e.g. subsist, substandard, mismatch, mistake, etc.· An s that is written next to an unvoiced consonant 清辅音 is always unvoiced /s/, e.g. lisp, rasp, history, etc. · When the unvoiced consonant of the above rule is [t], then the /t/ is silent if the next syllable is syllabic /n/ or /l/: listen, whistle. (Otherwise it is pronounced. See the comments for a more detailed description of this rule.)· An s before m is always voiced /z/: chasm, prism, plasma. However, the top rule takes precedence有优先权, so the s in mismatch is always voiceless /s/. · An s that is written doubled between vowels is also unvoiced: massive, missive, missile, etc. However, if the s would occur in the phonetic stream /s+j/ then it assimilates to /ʃ/, e.g. in mission.· An s that is written as one single letter between vowels is usually /z/, e.g. laser, risible, criticise/ criticize, desert, design, reason, busy, result, reserve, closer (the comparative form of the adjective "close", has an /s/ sound). In the same environment as mentioned above /z+j/ will assimilate to /ʒ/ e.g. in vision. · Terrible exception to the above: in dessert, the s is voiced to /z/. Many native English speakers misspell dessert for this reason. Note also that the difference between desert and dessert is not voicing, but which syllable gets the accent (it is the first in desert and the second in dessert). · Possess and its derivatives are another exception; the middle "ss" is voiced to /z/. The terminating "ss" is not.· Other miscellaneous exceptions: The -ss- in the American state name Missouri is also exceptionally pronounced /z/. In raspberry, the p is silent and the [s] assimilates to the /b/, so is voiced to /z/.补充：Based on the immediately surrounding letters:· Word-internal -ns-, e.g. in insist, tense, tinsel, is almost always pronounced /ns/ with unvoiced /s/. This doesn't apply to words that end in -ns, like pens or lens (these have /nz/). Exceptions: cleanse and pansy, which have /nz/. For some speakers, certain (but not necessarily all) words starting with "trans" such as transit and transition have /nz/.· Word-internal -ls-, e.g. in else, pulse, is almost always pronounced /ls/ with unvoiced /s/. This doesn't apply to words that end in -ls, like eels or steals (these have /lz/). Exception: palsy, which has /lz/.· Word-internal -rs-, e.g. in persist, verse, is almost always pronounced /rs/* with unvoiced /s/. This doesn't apply to words that end in -rs, like stars or yours (these have /rz/*).Based on identifying particular suffixes:· The ending -sive is usually pronounced /sɪv/ with voiceless /s/, even when there is a vowel letter immediately preceding the letter "s". For example, explosive, invasive, abusive, derisive are all pronounced with /s/. · The ending -osity is always pronounced with voiceless /s/.名词复数后面s的发音规则一般来说，s在元音或浊辅音后读[z}，在清辅音后面读成[s]，在[t]后与[t]在一起读成[ts]，在[d]后与[d]一起读成[dz]。
cups 杯子 days 日子 hands 手 hats 帽子2、以s,sh,ch,x结尾的词在词尾加－es，读[iz]classes 班级 buses 公共汽车 boxes 盒子 watches 手表3、以“元音字母＋y”结尾的词，加－s，读作[z]；以辅音字母＋y结尾的词，变y为i，再加－es，读[iz]boy-boys 男孩 army-armies 军队 story-stories 故事 factory-factories 工厂 baby-babies 宝贝4、以o结尾的词，多数加－s，读[z]kilo-kilos 公里 photo-photos 照片 tobacco-tobaccos 烟草 piano-pianos 钢琴以元音字母＋o结尾的词一律加－s，读[z]zoo-zoos 动物园 radio-radios 收音机少数以o结尾的词，在词尾加-es，读[z]tomato-tomatoes 西红柿 hero-heroes 英雄 Negro-Negroes 黑人 potato-potatoes 土豆5、以f或fe结尾的词，多数把f,fe变为v，再加－es，读[s]leaf-leaves 树叶 thief-thieves 小偷 wife-wives。