已知某变量分布属于钟形分布，且
，则()。
A:
B:
C:
D:
，则()。A:
B:
C:
D:
举一反三
- 已知某系统模拟图如图所示，则该系统数学模型为（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/7b331e776a454b34b3ce7514c85f55ce.png" ><img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/9b732439cb324b709c699aa7caf1bd43.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/3a6a819b0f204f1c861fa806fcff9bfa.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/296a376761a64a66a35f073904daa96f.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/6d22be023ff94910a3dc634670220912.png" >
- 亲核性最强的是（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/57e2c03b54f14a0a92e58cccdd920371.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/5bbbbff9b4b54e25b0e14eae38022d71.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/2ab00707a09546a1a47e7f577da4e52b.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/c092dc5bfa7e40ada1ec10b39bc5ac52.png" >
- 由苯合成<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/71faeb69bb654ff6bcb8317f2b46e805.png" >不合理的路线是（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/9a43529621dd442aa66725af170e8bbe.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/4ff9332196ec46359a0dcb19181be7aa.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/1a4c85721b604007937a62d2adec1f6a.png" >
- 下列属于{100}晶面族的晶面有（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/0add32d287a940f69e91fbae943eee76.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/13d75d49e079433096f649f812fc69a6.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/98be2e9d508448e48e920a1a5444366c.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/7e55102ed4254dd2ad54dd1c36e0dd2a.png">
- 若某系统的传递函数为G（s）=<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/40cffec1140048fda668f02b2697bfb6.png" >，则相应的频率特性G（jω）为（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/b0edaaca759a4b96b2746d371ba37485.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/17d6f581231244c386888754b3bf178d.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/e5485f9797b64853b91ce68c4697ff2e.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/5330c18e71b94abdbeaeff937486d18a.png" >