21~25 DACBD 26~30 ABDCB
31~35 DBACD 36~40 CDBBC
41~45 DCDBA 46~50 DADCC
51~55 AACBB 56~60 CBDBB
61~65 BBCDA 66~70 BABCD
71 improve
72 technology
73 storing
74 recognize
75 gives 或 offers
76 convenience
77 expensive
78 Problems
79 returned
80 instead
错了的话对不住啊~