—I like swimming best. Shall we go swimming this Saturday?
A:include
B:includes
C:including
D:included
如图所示的四个装置中,设计不合理的是( )
P1:∀(x,y)∈D,x+y+1≥0;
P2:∀(x,y)∈D,2x﹣y+2≤0;
P3:∃(x,y)∈D, y+1x−1 ≤﹣4;
P4:∃(x,y)∈D,x2+y2≤2.
其中真命题的是( )