一盒产品中有
只正品，
只次品，有放回地任取两次，第二次取到正品的概率为（）。
A:
B:
C:
D:
只正品，只次品，有放回地任取两次，第二次取到正品的概率为（）。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" >
- 已知某变量分布属于钟形分布，且<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/c3c68d24239b47e3908a9fa39d3026e5.png">，则()。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/c289a674c3a949efb63ebfd7f5e17f73.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/14899ead117944fd93b2513951e16161.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/94c95d1322d84ebf9c0a99328b06d62b.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/0f01a113b6e14ec8ac04e74d869aea49.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" >
- 下列手性碳原子为S构型的是（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/f26e98748b5f4febb87f5f729fa7e183.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/bddff733265d496783fc62fe08ae1bd7.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/be3096e7d3c345e2986ebacb04570b51.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/43a2967860564661ba5826a73a06629e.png" >