—What should we do before we use the blender?—I think we must read __________.
A:information
B:instructions
C:notes
D: opinions
(Ⅰ)求数列{an}的通项公式及前n项和Sn;
(Ⅱ)若递减等比数列{bn}满足:b2=a2,b4=a4,求数列{bn}的通项公式.