A:①②
B:①②④
C:①③④
D:①②③④
Did Mike have ______ accident when he was eight?( )
设等差数列an的前n项和为Sn,已知a6-13+2013a6-1=1,a2008-13+2013a2008-1=-1则下列结论中正确的是( )
文中总写大潮的句子是:“____。”写潮的描写顺序是 ____ 。