A:to help, enjoy
B:help, to enjoy
C:help, enjoying
D:to be helped, to enjoy
已知等差数列an的前n项和为Sn,a5=5,S5=15,则数列1anan-1的前100项和为 ( )
如图是消化系统模式图,请据图分析下列问题:
Going to the movies is good, ______ I really only like listening to music.