求下列差分方程所示系统的单位函数响应。[br][/br][tex=15.714x1.571]ziZ5yqsX4mT3YozRdEZXztY+IRns8RYqdNpZNEabnWGx4T4J7jEiEfROcnlgcezR[/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)

[tex=2.643x1.214]lNi1KUqX8sbmSHD/suIr6w==[/tex]的摩尔电导率与其离子的摩尔电导率的关系是 未知类型：{'options': ['[tex=15.714x1.571]h7Kc86tLK90zsAmbqNOZEya/c8nGfgVvFnWkKUt3Uk0jQhMQpLn+q9+ITLpGurlx5KwSbwj7bJYLiJvOTBE6xW6SIekz5uH/mKbn0xRTEY6/sY9yL4lcTskiIam4mgC2zoCsemJmKjo9aa3+DuVJmIcps+FAJ64NmH31ow/nYDaIoNpRdRyFs22BUq3RSoeq[/tex]', '[tex=16.786x2.357]h7Kc86tLK90zsAmbqNOZEya/c8nGfgVvFnWkKUt3Uk0jQhMQpLn+q9+ITLpGurlxLA1xdxy4F3ZCqFUxV5aq0R435//HzZ8xpFNquryNhLH9WHZTMgdpBt00lbSTWw2fLHHNMRnL3JJYx6r0bxsWupxxQk1PZIM0KzIxCgOrWI7KIrdZEGtgKLfoMcznr7JIASS5aPN27Q+fgsnZWSw1wA==[/tex]', '[tex=16.214x1.571]h7Kc86tLK90zsAmbqNOZEya/c8nGfgVvFnWkKUt3Uk0jQhMQpLn+q9+ITLpGurlx5KwSbwj7bJYLiJvOTBE6xW6SIekz5uH/mKbn0xRTEY683JpTo0QI+LwKUZ7kduPbAZwiYgrGWaSLgCBqB8oqsf6TgJOCeKhoIKfC7uowqrzsBOWmxf+l7QM8S0mX001u[/tex]', '[tex=17.214x1.571]h7Kc86tLK90zsAmbqNOZEya/c8nGfgVvFnWkKUt3Uk2T7EP3jneo8I6eColWrjUtzDXP23wal9CI3jbtMrTcbQMqYRz9D0p6lOSGr70/elN2tz5mIGIJ2vUwt/6PLcoygxwYXpRCgvKR/kuC4D6b/XgzOqXq1OBDevB35J0eWS+R6E3rlBBl5V6oyL1pnq3pKt0eHrkCN9SJ3cxPXMNxHw==[/tex]'], 'type': 102}

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)

以下谓词公式中，( )不是逻辑有效式。 A: ($x)(P(x)∧Q(x)) Þ ($x) P(x)∧($x) Q(x) B: ("x)(P(x)∧Q(x)) Þ ("x) P(x)∧("x) Q(x) C: ($x)(P(x)∧Q(x)) Û ($x) P(x)∧($x) Q(x) D: ("x)(P(x)∧Q(x)) Û ("x) P(x)∧("x) Q(x)

以下谓词公式中，( )不是逻辑有效式。 A: ($x) P(x)∨($x) Q(x) Þ ($x)(P(x)∨Q(x)) B: ("x) P(x)∨("x) Q(x) Þ ("x)(P(x)∨Q(x)) C: ($x) P(x)∨($x) Q(x) Û ($x)(P(x)∨Q(x)) D: ("x) P(x)∨("x) Q(x) Û ("x)(P(x)∨Q(x))

使用下述谓词：P(x): x是语言、Q(x): x是中间语言、R(x): x是世界通用的，及量词表示自然语句“没有语言是世界通用的话，就至少有一种中间语言存在”为（ ）。A.~($x)(P(x) Þ R(x)) Þ ($x) Q(x)B.~($x)(P(x)∧R(x)) ∧ ($x) Q(x) C.~($x)(P(x) Þ R(x)) ∧ ($x) Q(x) D.~($x)(P(x)∧R(x)) Þ ($x) Q(x) A: ~($x)(P(x) Þ R(x)) Þ ($x) Q(x) B: ~($x)(P(x)∧R(x)) ∧ ($x) Q(x) ~($x)(P(x) Þ R(x)) ∧ ($x) Q(x) D.~($x)(P(x)∧R(x)) Þ ($x) Q(x) C: ~($x)(P(x) Þ R(x)) ∧ ($x) Q(x) D: ~($x)(P(x)∧R(x)) Þ ($x) Q(x)