若电流表A示数为0，则R与I的值分别为：（ ）https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/11a5c4b9d6a54ba5a4a98545fa8217f4.png
举一反三
- 下列逻辑命题正确的是（）。 A: 若Y=A+B则<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/2ac821feb3d7451a8c7c69c97de1ca39.png">=<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/d900fde7b3dc4b2ea24859c0712ddd0c.png"> B: 若A+B=A+C则B=C C: 若Y=A+B则<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e305d54dd8c94adfaf570a2f0e6d4421.png">=<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/3cb33b429abf4ec397173f58dcdd37af.png">+<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/87aa5698238b4b66b9264426769b7b17.png"> D: 若AB=AC则B=C
- 使用4期简单移动平均作预测，求在2期预测值<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202011/bc8680b9736c4e539c8853c003bbe44a.png" />中<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202011/c5e366fc1bab4841946cf3d106c37d6d.png" />与<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202011/6bf0ccca11f2430fa6bddccad759dff1.png" />前面的系数分别为（ ）。 A: 1/16，5/4 B: 5/16，5/16 C: 5/16，4/16 D: 5/4，5/4
- 设随机变量X~N(4,2)，则其特征函数为(). A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/357ad388efa144a1a2b824e2b1ded239.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/d52e72841a81484981168cbb693bad24.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/00e1e0c2bba04889b58eb483c88821fb.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/1851c30670244a5c821128d6c44a3ecc.png" >
- 某最小相位系统的开环对数幅频特性曲线<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/bcd21e42b27341478945568b99d0e0e1.png" >如图所示，则其开环传递函数和相角裕度分别为（）。<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/84e4b98286924479ae7d38d3b0e5fd2f.png" > A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/b0eda84a8f794aaab38a2ca259435434.png" > B: 0° C: 16.3° D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/aa67284249764b51bb1c9fb836c2a9aa.png" >
- 序列<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202008/e1790a2df1984f8da7b286621e37686d.png" />的长度为4，序列<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202008/5bd332b1c2a443b6ad2642f7370c587d.png" />的长度为3，则它们线性卷积的长度和5点圆周卷积的长度分别是（ ）。 A: 7, 5 B: 5, 5 C: 6, 6 D: 6, 5