【判断题】
A、B、C是任意命题公式,如果A∧C<imgdata-url="doc/a@E84B3E63D310AD1116BA25407581A3DC.jpg"data-preview_url_ueditor="doc/a@E84B3E63D310AD1116BA25407581A3DC.jpg"src="http://121.251.253.213/doc/a@E84B3E63D310AD1116BA25407581A3DC.jpg/download?time=636160149056001750&token=2EAE2B04A9758637A941E72BB85B6BE5&filename=jpg"/>B∧C,一定有A<imgdata-url="doc/a@E84B3E63D310AD1116BA25407581A3DC.jpg"data-preview_url_ueditor="doc/a@E84B3E63D310AD1116BA25407581A3DC.jpg"src="http://121.251.253.213/doc/a@E84B3E63D310AD1116BA25407581A3DC.jpg/download?time=636160149137745894&token=DEFF417B0353B6D1F51C4963ABFDB837&filename=jpg"/>B。
【单选题】
<imgsrc="http://121.251.253.213/doc/a@25A8EE3D03B94A9F04D52345269684B2.png/download?time=636002469279516676&token=667DD112AFAE69C50B1A261A40FC4718&filename=png"data-url="doc/a@25A8EE3D03B94A9F04D52345269684B2.png"data-preview_url_ueditor="doc/a@25A8EE3D03B94A9F04D52345269684B2.png"/>
①
<imgsrc="http://121.251.253.213/doc/a@4EA15DA9D72B7EB9DB10D08648C08C67.png/download?time=636002469357204812&token=A3BD2200A91DEDBFD005F65BAF740481&filename=png"data-url="doc/a@4EA15DA9D72B7EB9DB10D08648C08C67.png"data-preview_url_ueditor="doc/a@4EA15DA9D72B7EB9DB10D08648C08C67.png"/>
②
<imgsrc="http://121.251.253.213/doc/a@652DB2CAA7F879DCDAFB1BB68E421DEB.png/download?time=636002469435984951&token=C0A6D39C3768EDD45CC4A7D5AE83EEBC&filename=png"data-url="doc/a@652DB2CAA7F879DCDAFB1BB68E421DEB.png"data-preview_url_ueditor="doc/a@652DB2CAA7F879DCDAFB1BB68E421DEB.png"/>
③
<imgsrc="http://121.251.253.213/doc/a@77F7CEF7772DDF237C280A444E2E16BD.png/download?time=636002469573889193&token=1ED3A1FE631AE91F328056D1EA6BB6FF&filename=png"data-url="doc/a@77F7CEF7772DDF237C280A444E2E16BD.png"data-preview_url_ueditor="doc/a@77F7CEF7772DDF237C280A444E2E16BD.png"/>
④
<imgsrc="http://121.251.253.213/doc/a@B54146B380619C725F9C9D89C3C6E2B5.png/download?time=636002469780901556&token=B067D315DA70A8FB600D7D11CE925E5B&filename=png"data-url="doc/a@B54146B380619C725F9C9D89C3C6E2B5.png"data-preview_url_ueditor="doc/a@B54146B380619C725F9C9D89C3C6E2B5.png"/>
【单选题】
<imgsrc="http://121.251.253.213/doc/a@C698C4ADC93D93531381824327A9FF44.png/download?time=636002474470581793&token=0B9B3D8B57AE0E63ECE153E923BCE509&filename=png"data-url="doc/a@C698C4ADC93D93531381824327A9FF44.png"data-preview_url_ueditor="doc/a@C698C4ADC93D93531381824327A9FF44.png"/>
①
<imgsrc="http://121.251.253.213/doc/a@CF33E559A85423D5CAB6EDCFECDC1DC7.png/download?time=636002474556069944&token=1F73253CE0DBDE683628F12C5F4D8450&filename=png"data-url="doc/a@CF33E559A85423D5CAB6EDCFECDC1DC7.png"data-preview_url_ueditor="doc/a@CF33E559A85423D5CAB6EDCFECDC1DC7.png"/>
②
<imgsrc="http://121.251.253.213/doc/a@60A71C811B81029FBF602DFB3E611403.png/download?time=636002474654194116&token=D3D19601DFC12A813BAA15BE2BFEF530&filename=png"data-url="doc/a@60A71C811B81029FBF602DFB3E611403.png"data-preview_url_ueditor="doc/a@60A71C811B81029FBF602DFB3E611403.png"/>
③
<imgsrc="http://121.251.253.213/doc/a@1CC11FD18C5106A0703556B59DF43E87.png/download?time=636002474737810263&token=CC4793C07577F75B877ADA52A41C1E24&filename=png"data-url="doc/a@1CC11FD18C5106A0703556B59DF43E87.png"data-preview_url_ueditor="doc/a@1CC11FD18C5106A0703556B59DF43E87.png"/>
④
<imgsrc="http://121.251.253.213/doc/a@147CD7754712A48704A0454D88895623.png/download?time=636002474844982451&token=3081AFA389E2249745935FD3A4A33759&filename=png"data-url="doc/a@147CD7754712A48704A0454D88895623.png"data-preview_url_ueditor="doc/a@147CD7754712A48704A0454D88895623.png"/>
【单选题】
<imgsrc="http://121.251.253.213/doc/a@2207FACE01D724A41FEAE521767FA8B6.png/download?time=636002470509734837&token=8C63F7DD30B5A8F399433B76BF18E3C9&filename=png"data-url="doc/a@2207FACE01D724A41FEAE521767FA8B6.png"data-preview_url_ueditor="doc/a@2207FACE01D724A41FEAE521767FA8B6.png"/>
①
<imgsrc="http://121.251.253.213/doc/a@9B95A2D1B6CA4AF4BFDE04D7D52EB9D4.png/download?time=636002470637343061&token=7AA0C37EAC3963A00C317B025C2047D6&filename=png"data-url="doc/a@9B95A2D1B6CA4AF4BFDE04D7D52EB9D4.png"data-preview_url_ueditor="doc/a@9B95A2D1B6CA4AF4BFDE04D7D52EB9D4.png"/>
②
<imgsrc="http://121.251.253.213/doc/a@675B12C6CBE318DDF85F641AB815E173.png/download?time=636002470709103187&token=B6A2AEAE2B9D81EA03BE98F45A066427&filename=png"data-url="doc/a@675B12C6CBE318DDF85F641AB815E173.png"data-preview_url_ueditor="doc/a@675B12C6CBE318DDF85F641AB815E173.png"/>
③
<imgsrc="http://121.251.253.213/doc/a@129CE6E27A8A7965ACB2BC93ADA9B65B.png/download?time=636002470820955383&token=CD066342C24F14945A36CBDFF5AEEBAD&filename=png"data-url="doc/a@129CE6E27A8A7965ACB2BC93ADA9B65B.png"data-preview_url_ueditor="doc/a@129CE6E27A8A7965ACB2BC93ADA9B65B.png"/>
④
<imgsrc="http://121.251.253.213/doc/a@D364096144FBDE93C84597F0FF9E6763.png/download?time=636002470907223535&token=FA7071F492DEB96139B2857A5F244CBF&filename=png"data-url="doc/a@D364096144FBDE93C84597F0FF9E6763.png"data-preview_url_ueditor="doc/a@D364096144FBDE93C84597F0FF9E6763.png"/>
【单选题】
<imgsrc="http://121.251.253.213/doc/a@C822C5255D1BFBC4EFF55E23D4FEA269.png/download?time=636002468341175028&token=CE6F6A3098A2546CA448994156A06B4F&filename=png"data-url="doc/a@C822C5255D1BFBC4EFF55E23D4FEA269.png"data-preview_url_ueditor="doc/a@C822C5255D1BFBC4EFF55E23D4FEA269.png"/>
①
<imgsrc="http://121.251.253.213/doc/a@DBEEBE73CFA7E73C6399957FED644156.png/download?time=636002468484851280&token=43D4A78B0932FDEAAE930017B2517CAC&filename=png"data-url="doc/a@DBEEBE73CFA7E73C6399957FED644156.png"data-preview_url_ueditor="doc/a@DBEEBE73CFA7E73C6399957FED644156.png"/>
②
<imgsrc="http://121.251.253.213/doc/a@46FC620B1AB1E78C4769EE7DEC50E108.png/download?time=636002468571743433&token=A4202C39CC5013BF42AC4A44EF5E4D77&filename=png"data-url="doc/a@46FC620B1AB1E78C4769EE7DEC50E108.png"data-preview_url_ueditor="doc/a@46FC620B1AB1E78C4769EE7DEC50E108.png"/>
③
<imgsrc="http://121.251.253.213/doc/a@6D0DDF8D51FC73666E0CAB6BFD87EC11.png/download?time=636002468660351588&token=77DA416D90A08F2FCD792C6C4373158D&filename=png"data-url="doc/a@6D0DDF8D51FC73666E0CAB6BFD87EC11.png"data-preview_url_ueditor="doc/a@6D0DDF8D51FC73666E0CAB6BFD87EC11.png"/>
④
<imgsrc="http://121.251.253.213/doc/a@B0F0D2D6CBE8FCD42A1FD6230EF28E9F.png/download?time=636002468776259792&token=DC997BA41CF7924924C2AFBC05991177&filename=png"data-url="doc/a@B0F0D2D6CBE8FCD42A1FD6230EF28E9F.png"data-preview_url_ueditor="doc/a@B0F0D2D6CBE8FCD42A1FD6230EF28E9F.png"/>
【单选题】
利用二元关系R的关系图求其对称闭包时,()
②
若两个结点间有一条单向边,则添加一条与其方向相反的边
④
若两个结点间没有边相连,则加上两条方向相反的边
【单选题】
<imgsrc="http://121.251.253.213/doc/a@62CCC9248E6C5CEC9ECB487FFBC2C519.png/download?time=636002476138068722&token=141D02AA787A7554363662D240011921&filename=png"data-url="doc/a@62CCC9248E6C5CEC9ECB487FFBC2C519.png"data-preview_url_ueditor="doc/a@62CCC9248E6C5CEC9ECB487FFBC2C519.png"/>
①
<imgsrc="http://121.251.253.213/doc/a@145B3AC53465C70D90DE0185C036A490.png/download?time=636002476212168852&token=AEBC4369C96DE92EF1B20DF70052F9C3&filename=png"data-url="doc/a@145B3AC53465C70D90DE0185C036A490.png"data-preview_url_ueditor="doc/a@145B3AC53465C70D90DE0185C036A490.png"/>
②
<imgsrc="http://121.251.253.213/doc/a@DBF4517EDFBD9FBFD42E1AEFD412897C.png/download?time=636002476292508993&token=DD1511B0D3AE73B8F5BF2C869A8F52F5&filename=png"data-url="doc/a@DBF4517EDFBD9FBFD42E1AEFD412897C.png"data-preview_url_ueditor="doc/a@DBF4517EDFBD9FBFD42E1AEFD412897C.png"/>
③
<imgsrc="http://121.251.253.213/doc/a@FD0B6F2E4606304A52FAF334BB5BC8E9.png/download?time=636002476370665131&token=D503206A410A9A758039EA014BC6A48F&filename=png"data-url="doc/a@FD0B6F2E4606304A52FAF334BB5BC8E9.png"data-preview_url_ueditor="doc/a@FD0B6F2E4606304A52FAF334BB5BC8E9.png"/>
④
<imgsrc="http://121.251.253.213/doc/a@1AAC94D22983B7C08A700950B6103C74.png/download?time=636002476446481264&token=7B31FF13B112C110C09DD7C42D18DC68&filename=png"data-url="doc/a@1AAC94D22983B7C08A700950B6103C74.png"data-preview_url_ueditor="doc/a@1AAC94D22983B7C08A700950B6103C74.png"/>
【单选题】
Q为有理数集,Q上定义运算*为a*b=a+b-ab,则<Q,*>的幺元为()