31. distinctive&distinct
　　distinctive “有特色的”，“独特的”；
　　distinct “清楚的，明显的”；a distinct smell of alcohol on his breath; the distinctive stripes of the zebra.
    
　　32. dual&duel
　　dual “二重的”；dual personality 双重人格；dual control 双重管辖；
　　duel “决斗，竞争”；fight a duel with sb. 与某人决斗；challenge sb. to a duel 向某人提出决斗；a duel of wits 斗智。
    
　　33. eatable&edible
　　eatable a. “可食用的，可吃的”；n. “食物、食品”。
　　edible a. “适合食用的，可以吃的”；n. “食品”。
　　在指吃的时候二者可通用：The toast was burnt and barely eatable/edible. 但在其他情况下不一样。
　　If something is eatable, it may be eaten (though it may not be safe or desirable to do so); but, if something is edible it is safe to eat.
    
　　34. economical&economic
　　economic “经济学的，经济上的” an economic survey of Scotland 苏格兰经济调查；an economic blockade 经济封锁；
　　economical “节俭的，经济的”；He's had to learn to be more economical now that his only income is a small pension.
    
　　35. evoke&invoke 
　　evoke “唤起，引起”；evoke admiration 引起羡慕。
　　invoke “祈求（神灵）保佑，乞灵于”，行使（法权）；If our case fails in the national courts we will invoke the European Declaration on Human Rights.
    
　　36. fatal&fateful
　　fatal “causing death or disaster” “致命的”； a fatal disease 不治之症；a fatal wound 致命伤。
　　fateful“crucial, significant, deciding one's fate” “重大的”，“决定性的，决定命运的”； On that one fateful day in October, millions of pounds werewiped off the value of shares.
    
　　37. fictional&fictitious
　　fictional “虚构的，小说的”；
　　fictitious “虚构的，编造的” (denotes something that is not real and has been created with the intention of deceiving others)；He gave the police afictitious name.
    
　　38. historical&historic
　　historical “有关历史的”，“历史的”, the historical period 历史阶段；historical personage 历史人物。
　　historic “历史上有名的，有历史意义的”，historic town 历史名城。
    
　　39. impassable&impassible
　　impassable “不能通行的”，“不可逾越的”；an impassable swam 不能通行的沼泽地。  
　　impassible “不感疼痛的；无动于衷的”； an impassible God 无动于衷的神。
    
　　40. infer&imply  
　　infer “猜想，臆测”，“推断”；infer a motive from an effect 从效果推知动机。  
　　imply “含有……的意思”； Do you realize what his words imply? 你领会他说话的含意吗？I do not imply that you are wrong. 我的意思不是说你错了。