题干
— Lily is about the competition.
— Yes, she is afraid that she won't win.
A：clear
B：nervous
C：happy
D：sure
答案(点此获取答案解析）
B
— Lily is about the competition.
— Yes, she is afraid that she won't win.
A：clear
B：nervous
C：happy
D：sure
，则数列
从首项到第几项的和最大