没有复数，因为luggage为不可数名词，中文意思是n. 行李精神负担

Do you have a lot of luggage?你的行李多吗

Two pieces of luggage have gone missing.有两件行李丢了。

There's room for one more piece of luggage.还有地方再放一件行李。

The dog was guarding its owner's luggage.