would have already been dead & would have already been died

Stenka25 wrote:

If they had lived in the days of capital punishment, they were already died. In the question, the answer is 'would have already died'. How about 1, or 2? 1. would have already been dead 2. would have already been died Is it ok to exchange the answer with 1. or 2? If not, why?

#1 is correct. The second option cannot be used because 'they would have already been died' is grammatically wrong. It should be 'they would have already died'.

Love should be died for is a highly irregular turn of phrase that comes from One should die for love.  It's treating die for as a prepositional verb.  It's not the passive form of die, but of die for, which is a highly suspect "verb".
Note that love is not died in this construction.  Nobody is "dying love", whatever that could possibly mean.  You can throw a ball, but you can't die love.

Compare:

The mayor should be relied on.

Here, the mayor is not relied.  Nobody is "relying the mayor".  That would be meaningless.
Instead, One should rely on the mayor.

CJ