开环系统频率特性
，当
时，其频率特性相角
（ ）。
A:
B:
C:
D:
，当时，其频率特性相角（ ）。A:
B:
C:
D:
举一反三
- 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">
- 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">
- 设开环系统频率特性为<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/d21a2327c99e49bd91ca22b052cbc0f6.png" />，则其频率特性的奈奎斯特图与负实轴交点的频率值<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/546cb297f51b4696b551151788da00a3.png" />为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/2007ab8a0021434b957556551bd9732d.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/2bbfd664c7ac40ad8014f612a59d6089.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/d30f9a3762d343d482c800ed0ef47e7c.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202108/5d17685250a34b2d8bd65e8b02b4325a.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" />;