这题肿么做啊?

这题肿么做啊? 如图,这题肿么做啊! We all know that Beijing held the 2008 Olympics on_______ evening of August 8,2008.A.an B.the C这题肿么做啊 Sn=3n²-n+1 求an用Sn-Sn-1算出an 可是当n=1时分别带入3n²-n+1和an得出的数不一样.这题肿么做啊0.0