Meals of the day.（一日"三"餐）
Breakfast in the morning.早餐
Lunch at the noon time.午餐
dinner in the eveing.晚餐
Snack anytime.任意时间点心

Question and answer 问答
Have you eaten yet? 你吃了吗？
Yes，I have eaten. 吃了。
No, I have not.

Have you eaten breakfast? 吃早饭了吗？
Yes. I have.吃了。
Have you eaten lunch? 吃午饭了吗？
Yes I have.吃了。
Have you eaten dinner? 吃晚饭了吗？
No, I have not. 没吃呢。