【正确答案】：
BACK-FORMATION IS THE METHOD OF CREATING WORDS BY REMOVING THE SUPPOSED SUFFIXES, WHILE BACK-CLIPPING IS A WAY TO SHORTEN A LONGER WORD BY CUTTING THE BACK PART OFF THE ORIGINAL AND USING WHAT REMAINS INSTEAD. PEOPLE MAKE VERBS BY DROPPING THE ENDINGS SUCH AS -ER AND -OR. WORDS CREATED THROUGH BACK-FORMATION ARE MOSTLY VERBS, FOR INSTANCE, DONATE (V.) FROM DONATION (N.), BEG (V.) FROM BEGGAR (N.), BABYSIT (V.) FROM BABYSITTER (N.) ETC. BACK-CLIPPED WORDS ARE JUST SHORTENED ONES, FOR EXAMPLE, DORM FOR DORMITORY, GENT FOR GENTLEMAN, BIKE FOR BICYCLE，MATHS FOR MATHEMATICS ETC.
【题目解析】：反转构词法是通过删除假定的后缀来创造新词的方法，而词尾截短是通过将原有的单词的词尾部分切下来并使用剩余部分来缩短较长单词的方法。人们通过丢弃诸如-er和-or之类的词尾将名词转化为动词。通过反转构词法产生的单词大多是动词，例如，donate（v.）来源于donation（n.）、beg（v.）来源于beggar（n.）、babysit（v.）来源于babysitter（n.）等等。词尾截短法就是单词的缩写，比如dorm是由dormitory去掉itory构成的，gent是由gentleman去掉leman构成的，bike是由bicycle转变而来的，maths是由mathematics转变而来的。