reverse(L) -> reverse(L, []).
reverse([], L) -> L;
reverse([H|T], L) -> reverse(T, [H|L]).
参数1============参数2
[1, 2, 3]===========[]
[1 | [2, 3]]==========[]
[2, 3]=============[1]
[2 | [3]]============[1]
[3]===============[2, 1]
[3 | [] ]=============[2, 1]
[]================[3, 2, 1]