下面这则广告中的形容词“irresistable”里的后缀( suffix)不对，应该把“-able”改为“-ible”：
“We offer: competitive monthly salary, weekly incentives, attractive transport allowance, incentive trips and irresistable performance bonus.”
到底是“-able”，还是“-ible”?这两者有何不同?
现在先从形容词的其他后缀谈起。
形容词后缀分两大类。一类是加到名词上的;另一类是加到动词上的。
㈠加到名词上的主要有：① -y，如：bloody, dirty, healthy, juicy, muddy; ② -ly，如：costly, friendly, lovely, orderly, timely;③ -ful，如：careful, faithful, helpful, peaceful, useful;④ -less，如：careless, harmless, noiseless, senseless, useless;⑤ -ous/-ious，如：dangerous; courageous, envious, mysterious;⑥ -al/-tal/-ial/-tial，如：accidental, horizontal, colonial, influential;⑦ -ic/-etic/-atic，如：artistic, sympathetic, systematic;⑧ -ish，如：childish, foolish, selfish;⑨ -like，如： life-like, business-like, war-like;⑩ -ed/-en，如：skilled, horned, golden, wooden.
㈡加到动词上的有：① -ent/-ant，如：dependent, different, observant, pleasant;② -able/-ible，如： agreeable, comfortable, defensible, sensible;③ -ive/-tive/-ative/-itive，如：active, attentive, imaginative, sensitive;④ -ed/-en，如：advanced, noted, stolen, swollen;⑤ -ing，如：annoying, disgusting, entertaining.
-able/ible 出现在第二类后缀中，“-able”后缀的形容词属英语体系的字：“-ible”后缀的形容词则来自拉丁体系。前者数量大，后者数量少，主要的是下面这些，可以特别留意：
accessible, apprehensible, audible, compatible, contemptible, convertible, corrigible, destructible, digestible, divisible, defensible, edible, eligible, exhaustible, fallible, feasible, flexible, forcible, horrible, illegible, intelligible, negligible, perceptible, possible, responsible, resistible, sensible, suspectible, tangible, terrible, visible.
现在顺便把名词、动词和副词主要后缀提出，作为参考：
⑴名词后缀
-ment, -t, -ture, -ion/-ition, -al, -ance, -ent, -er, -ant 等。这些名词后缀都要加到适当的动词上，如：arrangement, restraint, fixture, celebration, extension, competition, renewal, assistance, resident, exporter, attendant.
-ness, -y/-ty/-ity, -th, -ce/-cy 等，可以加到适当的形容词上如：darkness, kindness, honesty, loyalty, simplicity, truth, warmth, importance, absence, ungency, efficiency.
