【单选题】
设论域为整数集,下列真值为真的公式是( )
①
<imgwidth="116"height="20"src="../uploadfiles/word/lsss001.files/image023.png">
②
<imgwidth="116"height="20"src="../uploadfiles/word/lsss001.files/image024.png">
③
<imgwidth="119"height="20"src="../uploadfiles/word/lsss001.files/image025.png">
④
<imgwidth="134"height="20"src="../uploadfiles/word/lsss001.files/image026.png">
【单选题】
设个体域是整数集,则下列命题的真值为真的是( )
①
<imgwidth="9"height="13"src="../uploadfiles/word/lsss001.files/image050.png">y<imgwidth="9"height="11"src="../uploadfiles/word/lsss001.files/image051.png">x(x·y=1)
②
<imgwidth="9"height="11"src="../uploadfiles/word/lsss001.files/image051.png">x<imgwidth="9"height="13"src="../uploadfiles/word/lsss001.files/image050.png">y(x·y≠0)
③
<imgwidth="97"height="19"src="../uploadfiles/word/lsss001.files/image054.png">
④
<imgwidth="91"height="22"src="../uploadfiles/word/lsss001.files/image055.png">