The meaning of "harmony" and "or": the meaning of "harmony" is the same as that of "both at the same time", and the meaning of "or" is different from that of "either one or the other". Both will do. We should correctly understand the union and intersection of high school mathematics. If it is really hard to understand, imagine the trading set as a part of two * *, and the two are combined into one.

A∪B={x|x=2k or 2k- 1, k∈Z}

={x|x=k，k∈Z}

that is

A∪B=Z

For this problem, first observe two groups, because k belongs to an integer, a.

X=2K

No matter what value k takes, it must be an even set, B.

X=2K- 1, no matter what value K takes, it is a set of set numbers (if you don't understand it, you can use special value substitution method to verify it), then the union of A and B must be the sum of even and odd numbers, that is, all integers Z.