【单选题】
下列命题联结词集合中，是最小联结词组的是（ ）
①
{┐，<imgwidth="20"height="11"style="-aw-left-pos:0pt;-aw-rel-hpos:character;-aw-rel-vpos:line;-aw-top-pos:0pt;-aw-wrap-type:inline"src="../uploadfiles/word/lsss001.files/image077.png">}
②
{┐，∨，∧}
③
{┐，∧}
④
{∧，→}
【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">