可写成以下正确的的表达式是（）A:
B:
C:
D:
举一反三
- 下列各表达式不正确的是：（） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/3a28e3d5f36c4ef7819646bce49b8edf.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/1a6627e1deba4bd1a1b4b3b05a197bbc.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/98ab6999f98249bbbc3603d54db09a2d.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/dc1e9a6919a54bcaa28e1f8b876967de.png" >
- 下列表达式正确的是（） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/8c6704bb98b243b2a073149003ccd14d.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/538f492f0c844dfd95e11418fb2301fd.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/f03bb7b7f982489bb62780052c90f61c.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/0698ff5878ce447c801f7a69c87382b8.png" >
- 理想低通滤波器的传输函数<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/980b5b2a8d7044b697bc516003ea3acb.png" >是()。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/9a82e2e4ff27470da538512097ee6438.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c079877bd52d471db3cd6e163f62adbb.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/52aa9898f12641d797c40e4d118bd733.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/a7815d7407f34172aeef470a6adc5f47.png" >
- 单边拉普拉斯变换<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/423a53f9b3bf40989454133dbce2d262.png" >的原函数等于（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/301dd2111ac64b0e8217cba94ba1a1ab.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/9772eee6eab34c208eba55009d00041b.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/42bfb5f864e34b5ca02a2a1cc9d9c71b.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/659eef6ba24b490191772fe51bab3c9a.png" >
- 假定<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/71458e4f29a24928a4ad4d36e72ec6b9.png" >，以下关于z变换的性质描述，正确的是：（） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/545e8d644963417494a94eec7ae1bf50.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/04445d84fa3443968231a11a580079e2.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/5599b26833e546dfa3ab9c1c656c6581.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/fcc7d5135a714189b801863712e6b7f5.png" >