1.
□+□=□ 5−□=□
答案：2 + 3 = 5
5 - 2 = 3
2.
$2+2=□$
$4-3=□$
答案：$2+2=\boxed{4}$
$4-3=\boxed{1}$
3.
□ + □ = □
□ - □ = □
答案：$0+2=2$
$5-5=0$
4. $3-3=$ $0+5=$ $4+0=$
$3-0=$ $2-0=$ $4-4=$
答案：$3-3=0$
$0+5=5$
$4+0=4$
$3-0=3$
$2-0=2$
$4-4=0$
5. $5 - □ = 5$ $3 - □ = 0$ $□ + 0 = 4$
答案：$5 - \boxed{0} = 5$
$3 - \boxed{3} = 0$
$\boxed{4} + 0 = 4$
