A:①②
B:②④
C:②③
D:①③
Tom
Mary
Jack
Peter
Anna
I have many friends. What are they doing now?
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数列an的首项为3,bn 为等差数列且bn=an+1-an(n∈N*) .若则b3=-2,b10=12,则a8=( )
下列古代文学常识的说法错误的一项是( )