There was once a beautiful nymph called Echo. But Echo had one failing; she was fond of talking, and whether in chat or argument, would have the last word. As she was good company , she and Zeus becam
Most Chinese people these days know what it is like to have an “English teacher”, since almost all pupils study English from their third year. Usually that first English teacher will be a young an
展开式中的常数项为（ ）
C. 
20 D. 
