下列系统属于线性时不变系统的有：() A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/78aa235763d44041a95fd357a16bad1d.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/d3c8731be2c1407785e804f0fd44a132.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/eb9cabde15904190936a703ea658ef22.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/380f69e3088c4d2a99cca69b4f9546d5.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" >

已知Z变换Z<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/94487389db974f98b2d38b947ec20d83.png" >，收敛域<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/56b4868c286b4b48a8cec67f9f766670.png" >，则逆变换x（n）为()。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/547656863c8b459da97c366d9321ef13.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/d3572493bf964e2d92fde49d59b632af.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c4aacba69e0445b0ad4db797b3c86d53.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/b9af7d9dccb3446595a3a587492eb92a.png" >

空气与介质<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/1e6362735d6d4ae5a77aaafe5b5b49c7.png" />的分界面为z=0的平面，已知空气中的电场强度为<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/f8c5f3e89f4d4570a92c23bb118869fb.png" />,则介质中的电场强度<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/f7bb30061e904b39a8d53ad541435c18.png" />：() A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c1f29b60a07d4d75aa0f7e1c63a75a2f.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/74f128e456384ac79b8204c33052cbcc.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/c87cbdc5e75c40b4b875455ed5bccd28.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/b1117f3f152d413b89e5c221153014a8.png" />

<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/f9d435b7e7604d1894a0359bb77eb2cc.png" >可写成以下正确的的表达式是（） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/e68f9f4bb1b640068bd1c9e988b3feca.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/1b379e5c6cd74b5da61e39e4ca32ad22.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/44f6ba8e2d6448f4bec35063ad0f689f.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202002/e25be7e84d1e4f358bb44dacefafd393.png" >