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【简答题】
已知集合P={4，5，6}，Q={1，2，3}，定义P Q={x|x=p-q，p∈P，q∈Q}，则集合P Q的所有元素之和为（ ）。
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皮皮学刷刷变学霸
举一反三
【简答题】直接与室外空气接触的楼板或与不供暖供冷房间相邻的地板作为供暖供冷辐射地面时,必须设置( )。
【多选题】Born in 43 BCE, Ovid
A.
was a Silver Age poet who devoted his verses to patriotic themes.
B.
wrote love poems offering suggestions on how to seduce women.
C.
wrote the Metamorphoses which became the source of our knowledge of many classical myths.
D.
said: "whatever I tried to say, came out in verse."