Question

did you have breakfas和 have you had breakfast什么区别

一个是过去完成时，一个是现在完成时？

Answer 1

1 、have breakfast 是固定搭配，“吃早餐”的意思。
上述句子为一般疑问句。借助动词did 提前，真正的动词是have。
其陈述句：I had breakfast.
2 、Have you had your breakfast yet ?
Yes. Mom ( ) it for me.
A.was cooking
B.is cooking
C.will cook
D.cooked
Have you had your breakfast yet? - 你吃早餐了吗？（完成时态疑问句）
Yes. 吃了。（表示已经吃过）
Mom cooked it for me. 妈妈为我做的早餐。（是在你吃早餐前做的，所以用过去时态）
所以选择 D = cooked

3 、
did you have breakfast 语气上好像是不太关心到底吃了没，只是一种寒暄对话的感觉。吃或没吃对其根本没影响。
have you had breakfast？ 能感觉到提问人的关心，是其亲人亦或接下来要一起有什么活动的partner。完成时态嘛，考究的是对现在造成的影响或结果！