下列方程为伯努利方程的是（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/0622f56257874ab19e680d587fd8a4fc.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/5ce3fc785b724e3da7d07b8d6a0ecaf3.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/ab3de1c35e9e419fa301a33bddd5ee0c.png">+<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/2c226f2daecf40448b08c3b26a4db60e.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/88be95dd74814341a1894f32f073b9ec.png"><img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/00fbcbc7c3574f94934fa3adc8843ccf.png">

开环系统频率特性<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/d87c0f560f1542028a3602b52456fae0.png" />，当<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/c0f50539680f40a784c2a0d803f0f5d7.png" />时，其频率特性相角<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/ff41a81bec7c421c8178de199c438e05.png" />（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/589b5e2ab46b459882a2824ff9567c36.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/370b677492de485ca61114324b5d00fe.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/95723a2a938f4944a98b18d89f607986.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/c08161009369424f9a3510d7c77d9943.png" />

直线<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/64709df03a7b45ebbc6d752183b8f22e.png" />与直线<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/5ca5aa44859c42ddaa3207626d2b9537.png" />的公垂线方程为（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/a4c463fa2c3f49df9d7f2bb2e9fc4030.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/627b64a33e944efcba416aea0f40dc76.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/966e8a14e6754060b800dff88721784a.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/f8f41491de204a9eb3fb306208c3b08a.png" />

以下哪种图形表示选择结构（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/00e6d9ad2328497da022b3b20603d7f8.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/c6055ccfaafa4eafa3451f45a78535ae.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/b9cd7369284644b29d3499a3025d9cb3.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/8129afad6fcf46cb8c2d79c7e744809e.png">

下列方程中的恰当方程是（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/aa52759302af4380988847724495fb1e.png" />; B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/7d07e177cb1e4eb18a7d78e968236825.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/d2b71b62d9d4497ea01b423157f8e7ea.png" />； D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/2cec379e382a49f4a14a8a7280b96f6b.png" />;

下面哪个是正确的断句方式？（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/a2022b07bb4c416bb81f0d65515624ac.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/3f5d01772dbc4282a3fa21d4b77b5abf.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/9cd22fabfffb44dab7420779e166169e.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/443ccdfa5fb34ca7ad84367a69c376be.png" />

以下哪个公式是周期性功率信号的功率谱密度公式（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/fdca133567634aba8563a0e8202973e7.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/2d25894142c54b0a9841766e40f81a38.png"><img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/a1501c85213b49ca868ac8a509ce450a.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/faae4b3158d64835ac9ab19ca3623915.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/380fffd8c90340a6857c7bdb95721206.png">

请找出划线部分发音相同的一组单词（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/e35a67acf6d64372b1dbd71f0fa7b3bc.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/6e2ee1e75ead4317a6c561d59636374e.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/898275fe45d7467d9a82e961e96b4795.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/36d4cde9c34844b5a2c155dcb9f03602.png" />

下列性能指标中的（ ）为系统的稳态指标。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/14f12f89af1147c1acaedbcb38294237.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/e89d7e9ba7c14b7db9f8c58a52e89317.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/c3c17142d0a04a7b84588ca8b4730f32.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/aabfc0e7269843f9bfed3b6e3cd0421b.png" />

以下哪个公式是周期性功率信号的频谱公式（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/d866d2ef588941c592f11041e832b874.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/e96c211f3ae94824a5c743800a880c9a.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/31485515d551447dba1c8f91b27275f5.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/8f8844d055c2497fb4fde4750b229d7c.png">