We'll have a---holiday.what about going to the west lake?

C
表示 2天的假期用 two-day holiday,或：two days' holiday
再问： two-day是形容词吗？所以才可以修饰holiday？ 比如说，He is a____boy.so he can't go to the park by himself. six-year-old和six years old。那我应该选前者吗？那后者是什么性质呢？
再答： 你的理解很正确呀，就用six-year -old