def check_rectangle(arr,fex,fey):
    for i in arr:
        if i[0] > fex or i[1]>fey:
            print('NO')
            return
    print('YES')
    return

q = int(input().strip())
for _ in range(q):
    p = int(input().strip())
    arr = []
    for _ in range(p):
        t = [int(x) for x in input().strip().split()]
        arr.append(t)
    fex,fey = 0,0
    for i in arr:
        if i[0] != 0 and i[1] != 0:
            fex = i[0]
            fey = i[1]
            arr.remove(i)
    if fex==0 and fey==0:
        print('YES')
    else:
        check_rectangle(arr,fex,fey)