下列制备反应中，没有实际意义的是( )。
A:
B:
C:
D:
A:
B:
C:
D:
举一反三
- 信号通过匹配滤波器后的信噪比和信噪比增益为（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/ef96d88fe62b4c5ca109aa9ef7614e1e.png">，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/e3e80b9e3b4f46178d4121af624bf5cf.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/8c7bc2d622bc44d49f3b3c727edb7555.png">，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/4970bc3dbb644890931b6318f6c1d797.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/1e5de5cd5d2849b08a8451c2d16751e5.png">，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/17970f7191f24c6f861c0c1357e0d621.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/f804ad8708d9403d90f54fef1dcb4c72.png">，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/4970bc3dbb644890931b6318f6c1d797.png">
- 下列分子中，没有<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/a876746a1b6a4c35b918bdbc6cd6e5d1.png" />离域键的是( )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/36a350cfe47841088b4f2368b01fdf62.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/d97ba2811bb74bccb705c655c1dbca30.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/07448a3f91fe4fb3bad7f054df51c9ef.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/62fe3e693fef48a78e70c5aea62e9679.png" />
- 在<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />f和声小调中，构成属和弦的三个音是（ ） A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />C，E，G B: C，E，G C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />C，E，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />G D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />C，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />E，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />G
- <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/685431302ff949f2aa1ef6a730337dee.png" />，此旋律片段同时存在于下列哪组和声大小调式中（ ） A: C，c B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />A，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />a C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />D，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />d D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />B,<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />b
- 下列各组中哪两个音之间为自然全音（ ） A: B——<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />D B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />E——<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />F C: B——<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/eb254aec548342c5bb15b15aae65aaf6.png" />C D: A——<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202104/2141580b985544a086e54a919153ac07.png" />B