3.
在整数集\(Z\)中,被\(5\)除所得余数为\(k\)的所有整数组成一个“类”,记为\(\left[ \left. k \right. \right]\),则\(\left[ \left. k \right. \right]=\left[ \left. 5n+k \right. \right]\),\(k=0\),\(1\),\(2\),\(3\),\(4\),则下列结论正确的是__________\(.(\)填写序号\()\)
\(①2 018∈\)\(\left[ \left. 3 \right. \right]\)
; \(②Z=\)\(\left[ \left. 0 \right. \right]\)
\(∪\)\(\left[ \left. 1 \right. \right]\)
\(∪\)\(\left[ \left. 2 \right. \right]\)
\(∪\)\(\left[ \left. 3 \right. \right]\)
\(∪\)\(\left[ \left. 4 \right. \right]\)
; \(③\)“整数\(a\)、\(b\)属于同一\(‘\)类\(’\)”的充要条件是“\(a-b∈\)\(\left[ \left. 0 \right. \right]\)
”; \(④\)命题“整数\(a\)、\(b\)满足\(a∈\)\(\left[ \left. 1 \right. \right]\),\(b∈\)\(\left[ \left. 3 \right. \right]\),则\(a+b∈\)\(\left[ \left. 4 \right. \right]\)”的原命题与逆命题都为真命题.