Give a detailed description of tenses?

Answer 1

Linguists divide tenses into 'non-past' and 'past' as follows:

I go, I went

I am going, I was going

I have gone, I had gone

I have been going, I had been going

Adding auxiliaries like 'will' and 'could' gives:

I will go

I will be going

I will have gone

I will have been going

I could go

I could be going

I could have gone

I could have been going

The passive is formed as follows:

I am shaved, I was shaved

I am being shaved, I was being shaved

I have been shaved, I had been shaved

I have been being shaved, I had been being shaved

Of course, very many people avoid such a complex form as:

"That house has been being built for the last five years."

Instead the will convert it into the active voice saying:

"They have been building that house for the past five years."