依发电惯例，并励直流电动机的电压平衡方程可写成（ ）。
A:
B:
C:
D:
A:
B:
C:
D:
举一反三
- 已知<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/3b751d3b25514bec876427af5c1e59c1.png" />的z变换<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/6cd80d63c25f40f3930413d470be6bf3.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/44a7b63737404bcfab64da5ae36635f0.png" />的收敛域为（ ）时是因果序列。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/5ef40bb06be14e9099b67ab2070ee216.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/293e604c21c54aff8f2f0bb128871ad7.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/f8db782ebecd4e808769625106929a3f.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/67575d32d53542f9926a431d42780f0f.png" />
- 下面哪些是统计量?( ) A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/aa3c36f70a0c4b358e1e7bd04a5ca8af.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/fd47f763bd6549458e047323a31d160b.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/32739351c39446ca895b45108dbf1744.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/56142fe4e370488fa439dde57d347fe9.png" />
- 用户的密码信息保存在（ ）文件中 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/837734aa1d6c460aa86e32dcb50f6d1f.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/169bc5f6db044ca2aea8a23243ae708a.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/661c329523dd415489b340ba155d3acc.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/a7d915e53a1647179a02b51fa979282a.png" />
- 单位斜坡函数的拉氏变换是( ) A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/6c114780bb544390a8f6fe85300215d6.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/f2e3a0fab84042069b45b3693c3c862f.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/a37813a5aee4445aaa2353a9b049675a.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/3e3849360e7e4fb18baf98f8c408eec6.png" />
- c(NaCl) = 0.1mol/L的NaCl水溶液的质子平衡式是（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/9b7be57053c646c5aa738c0535f65770.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/b1382afa5c5d4951aef3b50dec2d582d.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/1887e7216893436fb1e402c407d2ffaa.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/c2d7158b33f44091a8b75598cbb3245d.png" />