from sys import stdin
def solve():
    n = int(stdin.readline())
    a = map(int, stdin.readline().split())
    a = [(x, i) for i, x in enumerate(a)]
    a.sort()
    if a[0][0] + a[1][0] <= a[-1][0]:
        t = [a[0][1] + 1, a[1][1] + 1, a[-1][1] + 1]
        t.sort()
        print t[0], t[1], t[2]
    else:
        print "IMPOSSIBLE"

T = int(stdin.readline())
for _ in xrange(T):
    solve()
