此处“That was the only time when I saw my dad drunk.”为什么用“drunk"

题目

此处“That was the only time when I saw my dad drunk.”为什么用“drunk"
“Let me go to my daddy; he needs me!” Ishouted.“No,Cindy,he’ll hurt you.You need to stay back,” my mom said to me.Then my dad came out carrying as much as he could.Without looking back,hewalked out of the door.That was the only time when I saw my dad drunk.And it was the first time when Isaw my hero fall.

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