+ 表达事实
The rabbit eats carrots.

+ 表达习惯/重复的动作
I play basketball.

+ 表示预计发生的事
The bus leaves 8pm tonight.

The rabbit is eating carrots.

The rabbit has eaten a carrot.
You have watched my video.

The rabbit has been eating carrots.
You have been watching my video.

+ 动作发生了
The rabbit ate a carrot.

You watched my video.

The rabbit was eating carrots.
You were watching my video.

I had eaten 5 carrots for lunch yesterday,so I wasn't hungry at all yesterday afternoon

+ 主要表达的是，对于昨天下午`yesterday afternoon时间点A` 来说，因为yesterday afternoon的过去`lunch yesterday时间点B`,我已经吃了一堆胡萝卜，所以B对A有影响，影响是 -> 我一点都不饿

+ 兔子在过去的时间已经在吃胡萝卜了，还要在那个时间点之后继续吃一段时间
The rabbit had been eating a carrot.

+ 你在过去某个时间点已经看我视频一段时间了，并且在那个时间点之后继续看一段时间
You had been watching my video

I will eat a carrot.
The sun will rise again tomorrow.

+ 描述将来某个时间，某个动作进行的过程中（笃定会发生）
I will be eating a carrot for lunch tomorrow from 1PM to 3PM

+ 更加笃定会发生的事情
The rabbit will have eaten a carrot.

I will have finished making the video by 4PM tomorrow,so I can publish it after that

+ 这里要表达的意思就是，对于4PM tomorrow这个时间点，我在那之前完成做完视频的动作，所以对4PM那时候有影响的，---什么影响--4点之后我就能发视频了

+ 将来某个时间观看我的视频，并且还要继续观看
You will have been watching my video.

I will have been eating carrots for 2 hours by 3PM tomorrow.

+ 这里要表达的是，我确定 3PM tomorrow时，我不但已经吃了俩钟头胡萝卜（也就是从明天下午1点开始吃），而且还要继续吃

I said I would eat a carrot for lunch
+ 午饭时间对于我之前说那句话时，是将来，但对于现在 午饭时间到没有到则未知

I knew you would watch my video
+ 看我视频这件事对于我作出这个knew判断来说是将来 

+ 我之前说我明天/昨天下午1点会吃胡萝卜（我之前说我明天/昨天下午1点会是在吃胡萝卜这个过程中）
I said I would be eating a carrot at 1PM tomorrow/yesterday

I said I would have eaten a carrot at 1PM  tomorrow/yesterday.
+ 我之前说我明天/昨天下午1点已经做完了吃胡萝卜这个动作

I said I would have been eating lunch for 2 hours by 1PM. tomorrow/yesterday.
+ 我之前说我会明天/昨天下午1点时在吃中饭这个过程中，之前吃了2钟头，还会继续吃