[tex=21.643x1.286]er6meh3Jhhk1HHWo3uk2ofSgLaxmxpN9xzfV8TEQOhA5uzai375In7zYozCTbnYsSCuSTB/aBHUEzguc744m+0mGnuyo8PTf/BMBrv0rPwc=[/tex]

[tex=32.0x1.286]Zx6q9Eiik52bctec3DobRMoJWKlhmHJZMV8NIFWpMqxvQpPWj7Xvpy8JJuBiH4OOkUuiLxYuDuoTQ8cpDwct3LIXRI1672q3V+mi90PkvLqxokyqXTMFJ25v18q7HI9Puq4PV0XPTfB/AQMuyg8Psg==[/tex][tex=25.071x1.286]SJOFrxCdoolEctGcWq1X/cpPuHxiTNIP6ffinN8a+1u4i1vllB3KyrDiMy21k4D0Ja3Cum9hABCRhzjxZcL7t0HxkWM6et03szPejY6Cd4R+0EGBf4cMmAzEvjHpjWuB[/tex][tex=21.643x1.286]AFUbcqNDUqs1iwl/dhwwcoQ3T2j5uTCIuxGFWJVid8FdcQC8H4/pt+4yyWkgUDUZ/oY/Ezh/sz0VHcugjiHx59DUfkrD7ErirF7tBYYhvs4=[/tex]

下列选项为某变速器一、二、三、四挡的传动比，则三挡的传动比为（）。 A: 0.969 B: 1.286 C: 1.944 D: 3.455

男性[tex=21.643x1.286]sOhcVhXK3vayNta8s1Bs8zj0HjtN/l/Kz+6ISZTFEc6kxvASI/2NSpaUaktnImAYu6OvxmPZhjjRcQMOAuHsvZXcAU8Soacxr+Bbyvqj3b4=[/tex]周后，拟行手术，首选手术方式是 未知类型：{'options': ['[tex=9.286x1.286]GnO+tB8rQfSbmgy87oXjHMwa1BqK2Nmy8BryKdb03DcjKEu0czMU0tpuj/A7k484[/tex]', '[tex=9.786x1.286]GnO+tB8rQfSbmgy87oXjHARvsAc1c/igeYsKs0o4JVF+vdFOL1esuoOzXnNh6VTN[/tex]', '高选择性迷走神经切断术', '全胃切除术', '胃模形切除术'], 'type': 102}

设有如图2.20所示的关系R和S，写出下列元组演算表达式表示的关系。[img=349x182]17e2dc45df28841.png[/img](1)[tex=9.714x1.357]V12q+5vCcawawArkId85R3pbcLmJRxFVzzp918kz+f5qL7W9Knml7GIslb6dS4+Z[/tex](2)[tex=10.0x1.357]cuMEun721XJPf4SsEq9Xi6wEEyxc+3jK+ae3N946NeXb/yVWWFgf63PVLIpIJlbl[/tex](3)[tex=21.643x1.286]92awPMKnMsuMrQpxQyw0pp3UO/FQPy7zZLmXD5mJ4SzaXr57WkjIisB6IMMSZyr43PkivoaQRnTEVXZIT7NPZB4TAfjN8NkH6fR4U7QuToaa/EYHDZ3PedkdgLxHRLT3PKyCFfVyQ08KlPyOpcBjnA==[/tex](4)[tex=19.929x1.286]CLFrMfU/uZW5m9Jaf0W66rudn5h4RS2kaZwtl2Bl2P2v+jaru2atoFuahRicKyAZL1R7zaJ0Rk/BGjG3FDXrH+qMweTKUSclNXhYgeRulUTLkNN5BYPo55y/6ztEHgB7[/tex]

下列变量组（）是一个闭回路。 A: {x，x，x，x，x，x} B: {x，x，x，x，x} C: {x，x，x，x，x，x} D: {x，x，x，x，x，x}

以下谓词蕴含式正确的是（）: (∀x) (A(x)→B(x))=>( ∀x)A(x)→(∀x)B(x)|(∀x) (A(x)↔B(x))=>( ∀x)A(x)↔(∀x)B(x)|(∀x)A(x)∨(∀x)B(x)=>( ∀x) (A(x)∨B(x))|(∃x) (A(x)∧B(x))=>(∃x)A(x)∧(∃x)B(x)

以下谓词蕴含式正确的是（）: (?x) (A(x)→B(x))=>( ?x)A(x)→(?x)B(x)|(?x) (A(x)?B(x))=>( ?x)A(x)?(?x)B(x)|(?x)A(x)∨(?x)B(x)=>( ?x) (A(x)∨B(x))|(?x) (A(x)∧B(x))=>(?x)A(x)∧(?x)B(x)

下列式中错误的是： A: (∀x)(A(x)Úp(x)) Û (∀x)A(x)Ú (∀x)p(x) B: ($x)A(x) Ù p Û ($x)(A(x) Ù p ) C: (∀x)(A(x)ÚB(x)) Þ (∀x)A(x)Ú( ∀x)B(x) D: ($x)(A(x)ÙB(x)) Þ ($x)A(x)Ù( $x)B(x)

判断下列推证是否正确。 (∀x)(A(x)→B(x))⇔(∀x)(￢A(x)∨B(x)) ⇔(∀x)￢( A(x)∧￢B(x) ) ⇔￢(∃x) ( A(x)∧￢B(x) ) ⇔￢( (∃x)A(x)∧(∃x)￢B(x) ) ⇔￢(∃x)A(x)∨￢(∃x)￢B(x) ⇔￢(∃x)A(x)∨(∀x)B(x) ⇔(∃x)A(x)→(∀x)B(x)