。假定舒张压之差服从正态分布，问在
水平上该中药对治疗高血压是否有效，其假设为
。（ ）
举一反三
- 系统的开环传函为<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/4c0fd44e4fd34ba5abebcf5cf4075e5b.png" />，根轨迹和虚轴的交点及相应的根轨迹增益为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/1a01ea0a12204b8395a0b5b77f6dff14.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/5973aa4feb8b449e936c4db36ba0f235.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/3212607aceba42119e02c092ee59c4c9.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/5e06d749351c40758f2d90bd5503ac41.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/646b41ca995f4f9883b1d2c4a17a1b4c.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/f268e2b90534408293cc995f99bf8907.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/212d583db0b74c5a84acfc955c422863.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/5e06d749351c40758f2d90bd5503ac41.png" />
- 考虑AR(2)模型<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/9c19d336a086430cab947cf3a40c8047.png" />,则AR特征方程的根为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/b8d42e894377426eaca4f3a382c0569c.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/cb2410db797c4dc5870eb9ab1dfae59e.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/505155f9e5654d3294291a0f104fd54f.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/ff900163e913414384b61dbd55a0c36e.png" />
- 函数<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/82f8c419da9c41f9b86e94ae2b2bcaf5.png" />的拉普拉斯逆变换为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/ed47adacefc64ac5afdfd39b57836c33.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/63ca53741edf465089db1557fb3d842a.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/744c576c1fe24e83aca105adcd700936.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/9699edb62c4c452eaac4b533c11e951a.png" />
- <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/78ba624fbf734c1d9af5e00e4b9c2044.png" />的Laplace变换为（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/ce12c2b6f25745f3a613f524ab3f0a15.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/1ac3b7dcc46848719b73c1751203b3f3.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/c5e3953d9bb040dd9b99aa8b1a9909bb.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/0ba32254e04f49eeaf592ef9fcbe6142.png" />
- <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/2f2539faa2cb42939c3a676ef42f909a.png" />的Laplace变换为（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/d7d45e2a8a32472090116ea10729421f.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/ecf689c55bf744a1be41c63e466ef916.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/a112c4e5f6c9443395f3fe1df0cb38b9.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/38f822b0273a407ba6d2d6b7351f4bdf.png" />
内容
- 0
<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/23eaf76ea4d840179921b8efeac91897.png" />的Laplace变换为（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/87f05a19f54c490f9e668a1b37b0e379.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/cefc4d67b0654ea3abe41386204117b9.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/4adb3e12b3584921855bf17691ed26da.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/722360ad93cc466da9f4d64b6a486bb2.png" />
- 1
下图所示信号流图的系统函数H(s)为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/604e89d38c214db9888de2246d102c7d.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/2c4320180d5d4f3f95463260a6586a1a.png" /><img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/42cd36c1dd634c79abcf9dfb185d3cbf.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/477a9f5c243046079c5500071f3d0414.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/9724865a860b4e7ba0b91e26c6ccf48d.png" />
- 2
已知逻辑函数<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/f78a8e8e624e4a69889e25d72ab9c5a2.png" />，与其相等的函数是（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/8bfde7b3a8ec424db65bd3358aea5a25.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/65e3c0d6ffae4c1e80f35b4b11f259fa.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/e8aa085d73754ae0a6f75b2dab413ed3.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/65c5c76097834e759836444e84540519.png" />
- 3
双向晶闸管的触发方式有（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/cdc835a9aa7547ff93e50e7d71486790.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/d055299fe26a47a088591ad2bcc05e56.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/c3d98aca32654bf88e41277f2e78a7a8.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/a5ca76b70f86430699510d037c2fe415.png" />
- 4
下列不是保护电器的是（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/24bd94ed502f4276b3e3839cd66fa5cd.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/8a0b42968bdf4de38d44d25060b50008.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/41f6e141c35549168d578386690cac27.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/9a5a11b3414a4a4289896e2f43b9a2b7.png" />