T = int(input())
for _ in range(T):
    N = int(input())
    res = list(range(1, N + 1))
    if N % 2 == 0:
        for i in range(0, N, 2):
            res[i], res[i+1] = res[i+1], res[i]
    else:
        for i in range(0, N - 3, 2):
            res[i], res[i+1] = res[i+1], res[i]
        res[N-3], res[N-2], res[N-1] = res[N-1], res[N-3], res[N-2]
    print(' '.join(map(str, res)))