had ... could have

[Mr. X]

Hello!

In past conditional III, it is okay to have any combination? Had he been there, he could have saved them. (here, had is followed by could have). So for different contexts, can we use a different verb, such as shoud/would etc.?

Or, is 'had' only followed by 'would have'?

Mr. X

 

[Raymott]

Hello!

In past conditional III, it is okay to have any combination? Had he been there, he could have saved them. (here, had is followed by could have). So for different contexts, can we use a different verb, such as shoud/would etc.?

Or, is 'had' only followed by 'would have'?

Mr. X

You can say whatever is appropriate, eg:
"Had he been there, he should have saved them."
"If he had been there, he might have saved them."

But you can't necessarily call these sentences examples of the 3rd conditional. That's not usually a problem though. If you are asked in an exam for a conditional sentence, use 'would'.