下列谓词公式中，是逻辑有效式的是（ ）。
A:
B:
C:
D:
A:
B:
C:
D:
举一反三
- 设A=<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/bc546fc03fdb4ba3b7e6b144b6371d7f.png" />，B=Р(Р(A)) 下列（ ）表达式不成立。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/6e615703da60435893f9e9a9273e12e5.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/64c831067d054e71a6c76f43849d450d.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/72023a5250e44c12b98923044194f13d.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/c48e039a739c4502830eee7ae0ac1678.png" />
- 下列谓词公式中，( )是等值的。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/3ad0f562353b4463b9b31a3a773c1153.png"> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/85d2bd83d84b43dc83ba5c1749871d69.png"> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/0b76f52c16ba411f96a0030d91b4f8b9.png"> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/4f1748ea22f049dea7381c3f1171c079.png">
- 下列电极电势最小的是： A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/dad3349a56e84119aff354de027c99e1.png"/> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/980bfc83fd624e14ab4d98cc5b6f71dd.png"/> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/a54b31ea021644c788a5c687342ced4d.png"/> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/8851284b569348549a0a28ded6b2cff1.png"/>
- 关于螺纹画法,正确的是 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/9ccba4619f94435c98b9ae7570b942d9.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/4bc6e6bda3eb4599aac46a7006ed3c17.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/cbdbd84b5748432d8d69e846b62109af.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/177c1236fbdd49ee899e6f362f3211e6.png" />
- 已知主视图和俯视图，下面左视图画法正确的有（ ）<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/2bcab5bbb4024d99b27781c7c286d861.png" /> A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/c740df10c8d64a5c9f269c0808cfba30.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/d19031d8c17543f699d8827fa6ac1249.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/1780a38439af44618170b420943a6b6d.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/202002/8b29c3cc4c2e4f3e919c5f22d4ac96f1.png" />