1 . 下列命题中①“
,
”的否定;②
,
;③若“
,则
”的逆命题;④“若
,则
”的逆否命题,则正确命题的序号为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0c7a319f1fb9ef4cd6bd9eb5ab0c53b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df62f80ddca67284233c37c026e4c820.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c780149aef1bd77162e85f7f8906a6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c2eea02872961e245942288edcee3f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f29cc76965fd5fb99578056056589bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08115d6d9f876dea921a4d32260ff1fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43a5abe56c019ac914e1fcde1865a747.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7428286645d4493a66d3231e3d907b58.png)
您最近一年使用:0次
2 . 下列说法中不正确的是________ .(填序号)
①若
,则“
”是“
”的必要不充分条件;
②“
为真命题”是“
为真命题”的必要不充分条件;
③若命题![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58952ef6586cdd46086cd2acef0d41d6.png)
,则
是真命题;
④命题“
”的否定是“
”.
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/848c33e3506416358d9f0d3ee66f67a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03788c7bd5b9c006b33452100cc1a054.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1edc21a2299cf3e51e60186e5fab8b2.png)
②“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/630acef0ef97721e9f030fb97705a49c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5638809efbb980cee614de77d718114.png)
③若命题
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58952ef6586cdd46086cd2acef0d41d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/feed65016bec4e09cd88dc6de79aeb93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e434d52b7741e42c21c2785eb07ffcaf.png)
④命题“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4884ab84c61111dc8057f819f10ca6c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30899fa8555b7b09960d9ecf87adddd2.png)
您最近一年使用:0次