A:卵细胞
B:精子或卵细胞
C:精子
D:精子和卵细胞
已知等差数列{an)的前n项和为Sn=﹣n2+(10+k)n+(k﹣1),则实数k=____ ,an=____
Our teacher often asks us ____________ questions in groups.
王师傅生产110个零件,个个合格,合格率是110%.