用数学归纳法证明等式1+2+3+…+（2n+1）=（n+1）（2n+1）时，当n 发布时间：2017-05-19 11:10 │ 来源：www.tikuol.com 题型：填空题 问题： 用数学归纳法证明等式1+2+3+…+（2n+1）=（n+1）（2n+1）时，当n=1左边所得的项是1+2+3；从“k→k+1”需增添的项是______．
题型：填空题 As he ______ to his work that he didn't notice that it was already past midnight. A. was so busy B. so devoted C. was so devoted D. was so turned 查看答案