【正确答案】：
ANTONYMS CAN BE DEFINED AS WORDS WHICH ARE OPPOSITE IN MEANING.  THEY CAN BE CLASSIFIED INTO THREE MAJOR GROUPS：CONTRADICTORY TERMS；CONTRARY TERMS；RELATIVE TERMS. 
1.RELATIVE TERMS: CONSISTS OF RELATIONAL OPPOSITES SUCH AS SELL/BUY. SUCH PAIRS OF WORDS INDICATE SUCH A RECIPROCAL SOCIAL RELATIONSHIP THAT ONE OF THEM CANNOT BE USED WITHOUT SUGGESTING THE OTHER.
2.CONTRADICTORY TERMS: THEY ARE SO OPPOSED TO EACH OTHER THAT THEY ARE MUTUALLY EXCLUSIVE AND ADMIT NO POSSIBILITY BETWEEN THEM, SUCH AS SAME/DIFFERENT. ONE THING IS EITHER SAME OR DIFFERENT, AND THERE EXISTS NO SUCH A CASE WHERE THE THING IS BOTH SAME AND DIFFERENT.
3.CONTRARY TERMS ARE BEST VIEWED IN TERMS OF A SCALE RUNNING BETWEEN TWO POLES OR EXTREMES, SUCH AS OLD/YOUNG.  
【题目解析】：反义词可以定义为意义相反的词。他们可以分为三大组:矛盾反义词、对立反义词和关系反义词。1.关系反义词：由诸如：卖/买等关系对立词组成。这样的词组表明了这样一种互惠的社会关系，以至于其中之一在使用时不能不暗示另一个。2.矛盾反义词：它们彼此对立，相互排斥，彼此之间不允许有任何可能性，比如：相同/不同。一样东西可以是相同或不同的（只有一种可能性），但不存在这样的情况——事物既相同又不同。3.对立反义词：最好用两个极点或极点（如：老/年轻）之间的比例来衡量。就好比老的和年轻的，是老还是年轻的需要衡量得出。