【正确答案】：
（1）INTERNAL FACTORS: SUCH CHANGE OCCURS WHEN A PHRASE IS SHORTENED TO ONE WORD WHICH RETAINS THE MEANING OF THE WHOLE, E.G. GOLD IS USED FOR 'GOLD MEDAL', AND BULB FOR 'LIGHT BULB'.
（2）THE INFLUX OF BORROWINGS: SUCH CHANGE OCCURS WHEN THE BORROWINGS ARE INTRODUCED INTO ENGLISH VOCABULARY. FOR INSTANCE, DEER FORMERLY MEANT ANIMAL, AND LATER ANIMAL FROM LATIN AND BEAST FROM FRENCH FOUND THEIR WAY INTO ENGLISH. AS THE THREE TERMS WERE SYNONYMOUS, ANIMAL RETAINED THE ORIGINAL MEANING, THE MEANING OF DEER WAS NARROWED AND BEAST CHANGED IN COLOUR. 
（3）ANALOGY: SUCH CHANGE OCCURS WHEN ANALOGY IS USED. FOR INSTANCE, FORTUITOUS FORMERLY DENOTED 'HAPPENING BY CHANCE', 'ACCIDENTAL' AND LATER TOOK ON THE MEANING 'FORTUNATE' PROBABLY BY ANALOGY BECAUSE THE TWO WORDS LOOK SIMILAR. IT IS THE SAME WITH FRUITION. THE ORIGINAL MEANING BEING' A PLEASURE OBTAINED FROM USING OR POSSESSING SOMETHING', WHICH HAD NOTHING TO DO WITH FRUIT. ITS MEANING OF 'THE BEARING OF FRUIT' WAS DUE TO THE LATER ASSOCIATION WITH THE WORD FRUIT. 
【题目解析】：（1）内部因素：当一个短语被缩短为一个保留整体含义的单词时，就会发生这种变化，例如用“金色”表示“金牌”，用“电灯泡”表示“灯泡”。（2）借词的流入：当借词被引入英语词汇时，就会发生这种变化。例如，“鹿”以前的意思是动物，后来拉丁语的“动物”和“法语”的野兽进入了英语。由于这三个术语是同义的，所以“动物”保留了原来的意思，“鹿”的意思（范围）变小了，“野兽”的这个词的色彩（词的性质）也变了。（3）类比：使用类比时会发生这种变化。例如，“偶然”以前指“偶然发生”，“偶然发生”后来又指“幸运”，可能是类似，因为这两个词看起来很相似。水果这个词也是如此。最初的意思是“从使用或拥有某物中获得的乐趣”，与水果无关。其“结果”的意思是由于后来与“果”这个词联系在一起。