I did have my hair dyed = I had my hair dyed
都屬過去式.
I did have my hair dyed 加強了說話的語氣, 特別是在對方不相信你會染髮時用.
其他例句:
例如你爸爸懷疑你今天沒有上學, 他會問你
Did you go to school today?
如你確實有上學, 你可以說 I did go to school today, 強調你有上學
有例如老師想知道或懷疑功課是不是你做的, 他問你
Did you do it yourself?
你可以答 I did do it myself 強調功課是自己做的.