Future simple passive and “be able to”

Question

I know “can” can’t be used in the future tense, where “be able to” is used instead.

How can I use “be able to” in future simple/continuous/perfect in passive voice?

Can I see examples?

Answer 1

As per my edits to your question, this is easier to answer if you think about the string “be able to” and not “to be able” or “to be able to”. Here are the simple, continuous, and perfect of an active verb in the future tense:

will write — will be writing — will have written

The corresponding passives are:

will be written — will be being written — will have been written

You add the periphrastic modal “be able to” after the future modal “will”:

will be able to be written — will be able to be being written — will be able to have been written

These correspond to the conditionals (where “can” can be used):

could be written — could be being written — could have been written

(There is some flexibility as to ordering, depending on what you mean exactly. E.g., both “will be able to have been written” and “will have been able to be written” are fine, but with subtly different meanings.)