1)if someone asks you"what r u doing", u can answer that. 2)if someone asks you"what did u eat for dinner?",u can say that u ate some rice. 3)if dinner time is coming, you can say"i'm going to have a meal" to your friend.It just means that it's time for dinner. 4)if your mother asked you"have u eaten lunch?",while you can tell her you have done that and emphasized that you have eaten some rice.

How to translate them into English depends on what the questions are. Q: What are you doing? (你在干什么？) A： I am eating.(我吃饭。) Q：Why do you stop work at 11 am?(你为什么停止工作？) A：I eat (at that time). 我吃饭了。 Q：Have you eaten breakfast? 你吃过早饭了吗 A：Yes, I have.( 我吃了饭 or 我吃了饭了) If much work hasn't finished, you feel hungry. You want to leave for lunch. You can say to colleague, "I'll eat something". 我吃饭了

I have a meal. I've had a meal./I had a meal. I'm going to have a meal. Doesn't make sense.

我一直分不清最后三个句子。据Yan所说，第一句是「我正在吃饭」，也可以出现在「我吃饭时不小心把口腔黏膜咬伤了／我开始吃饭后感到腰部痛出气」等类句子，第二句是「我吃了(米)饭」，第三句是「饭已经做好了。现在是吃饭时间了」，第四句是「我已经吃过饭了(所以不饿)」。我理解得对吗？

Kelsi，谢谢你的评论。但是你的解释还是有问题。第三句与第四句并不是将来事态的动作或状态。