derivational morphemes ：派生语素, when they conjoined to other morphems（or words）,new words are derived,or formed （指前缀和后缀的变化）
Eg：inter+collegiate affection+ate physic+ian
inflectional morphemes:屈折语素 the bound morphmes signifying such concepts as tense,number,case and so on （指时态,量词的变化）
Eg:John has noticed the change in his friends. He was walking to the station
--ing, --ed are mophemes which do not add any lexical meaning but represent the concept of tenxe and aspect.