should have been Ving

[ridvann]

Hi,

We're doing things we should have been doing 40 years ago in space.
Perhaps they should have been doing so, but they weren't..

He says Reyngoudt must have been wearing long pants when he first started coming into his shop because it took months until Walsh noticed his leg.

I have found these sentences on internet, and could you please tell me how to use these constructions, and could you tell me whether they are used for the past actions only or not?

Thanks...

 

[5jj]

We're doing things we should have been doing 40 years ago in space.
Perhaps they should have been doing so, but they weren't.

He says Reyngoudt must have been wearing long pants when he first started coming into his shop because it took months until Walsh noticed his leg.

The context tells us that the speaker is referring to the past in those sentences.

While the actions referred to started in the past, they may continue up to the present:

Why is John still in bed? He should have been manning the desk for two hours now.
She's frozen stiff. She must have been lying there for hours.

 

[ridvann]

There is no any form with 'can have been V ing' and 'ought to have been V ing. Is that right?

Only

Could -should -would -may -might + have been ______ing

Is that right?

 

[5jj]

There is no [STRIKE]any[/STRIKE] form with 'can have been V ing' and 'ought to have been V ing. Is that right? No.

'Can have been' plus the -ing form of the verb is posssible in sentences that begin with a negative word/phrase/clause:

Nobody can have been working yesterday; nothing has been moved since Tuesday.
I don't think anyone can have been working; ....

The negative form is fine:

They cant' have been working; ...
'Ought to have been' plus the -ing form is fine:

You ought to have been working on that when the boss dropped in.

 

[ridvann]

'Can have been' plus the -ing form of the verb is posssible in sentences that begin with a negative word/phrase/clause:[/I]

This form is in use for 'can't have + verb3' too, is that right?

For example: I don't think he can have bought it cheaply.

Is that fine?

Thanks...

 

[bhaisahab]

This form is in use for 'can't have + verb3' too, is that right?

For example: I don't think he can have bought it cheaply.

Is that fine?

Thanks...

Yes, that's fine.