I did have a very good time at the ball.这句中"did have" 是个什么用法

I did have a very good time at the ball.这句中"did have" 是个什么用法 Did you have a good time at the party, Linda Did you have a good time at the party last night?改为同义句 Did y Did you have a good time at the party?为什么用at? did you have a good time at laura's birthday party?surely .i you have a very good time,did not you 是什么语法 什么句型? did you have a good time at the party怎么改 Did you have a good time at the party yesterday evening ,Lis ．--Did Mike have a good time at the party?--Yes．He said that Did you have a good time in the USA? 翻译Did you have a good time during the holidays? Did you have a good time in the holiday?