Jack Ripper was ________ for murdering many people in the nineteenth century.
A:spectacular
B:popular
C:notorious
D:specific
科技书9.80元/本,故事书8.50元/本,两本书共____元,两本书相差____元。
反比例函数y=1x的图象在( )
设Sn为等比数列{an}的前n项和,若8a2-a5=0则S4S2=( )