A:
B:
C:
D:
(Ⅰ)求数列{an}的通项公式;
(Ⅱ)设bn= 2an +(﹣1)nan,求数列{bn}的前2n项和.
法国资产阶级革命开始的标志是 ( )
— What did the teacher say just now?
— He asked them _______ the math problem.