∴p2^2×p4^4=2×4×3×2× 1=48;
(2) The total number of five people queuing for free: p55 = 5× 4× 3× 2×1=120,
∴ 120-48=72;
Answer: If two people must be adjacent, there are 48 different ways to queue.
If two people can't be adjacent, there are 72 different ways to queue.