实直线
上的每一个紧致子空间都是闭的。（ ）
上的每一个紧致子空间都是闭的。（ ）
举一反三
- 已知 f (t)，为求<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/1fb776d0006a4eb2b93e07afcad58896.png" />则下列运算正确的是（其中<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/ada31d4207fe47d4908574b0a478486b.png" />， a 为正数）（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/fb0a09472a6b4408b3e833c2568308db.png" />左移<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/ada31d4207fe47d4908574b0a478486b.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/fb0a09472a6b4408b3e833c2568308db.png" />右移 C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/06dbb96ce1044280b13167a33033e4c6.png" />左移<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/ada31d4207fe47d4908574b0a478486b.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/06dbb96ce1044280b13167a33033e4c6.png" />右移
- 已知<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/0b6bd03a30394de5866eb04046000d07.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/aced01bc1bc24d49a068c754294b44e3.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/8872a86bb2a9457dace1176d21809909.png" />，用拉普拉斯变换法解微分方程<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/8ae2532227474de1bbdb5326fb2a05ec.png" />的零输入响应和零状态响应为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/5dac342ceb7141799376d81642c7bd17.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/c6491375b34b48ea9e1aa1e3cfda2c51.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/12c8d30af4244ab89d52eb7203d6d3a7.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/72758b4605f24d69a235afc727a0b877.png" />
- 下列分布函数性质的叙述中错误的是（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/aa7be662728549808e1e31a941f40586.png" />是右连续函数，即<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/3d2dd341bbb34bc49c6c16a0648e73a0.png" />; B: 对任意一个实数<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/6af90c1b0d1a4a2e9f52db02fba49eb3.png" />，都有<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/76a52406d5984c29b26b56770cd45589.png" />. C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/700eb5d94c754071b3fabc46105a97e5.png" />,<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/15b2abeddbab4e798304b38ed7d0a073.png" />; D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/25cc87b8d99c4475861371e994a4a857.png" />是<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/b62c2e7b67af45a28d3b1d079dd4ffd0.png" />单调非减函数;
- 已知某系统的数学模型为<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/36eb028cda9447468911e236a321722e.png" />，那么系统的沖激响应<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/2a6ea359e85c408fbece93c2e81f6076.png" />为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/2c5c40b2c9f84205812addf9df60664b.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/d1350a891d364096858a5f83a7415ece.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/e1352972cbd24aacb663ce6ef7fc95fc.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/1c91057ec86848a1b761ccb26b3ed883.png" />
- 试求序列<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/cb5683e4401b464bb94af075183c06d2.png" />的双边z变换及其收敛域（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/07475602a8b04ef18fe697ba033d87cc.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/9d0ea6592c7d45a28bb6dac86e53ca52.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/d594b5541bf8465d9eca5af4a3b38545.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202101/ddd3f7717f134d54a0e27eef90e3b930.png" />