the linking verb To BE(see how I used an article showing it's a specific linking verb?)
And to take us through the entire conjugation is TEFL Songs
will have been
would have been
In answer to Hamlet, I choose NOT TO BE, as most linking verbs are passive.
Are you doing the A to Z challenge? Let me know and I'll be sure to come by and say hello. Have any thoughts on To Be? Hamlet? Getting stung by bees because you're not sure if you're supposed to use have been or has been?