I would have finished my home work by evening .
He should have been more careful.
Can these be used as future perfect tense ?
The sentences under discussion are in the conditional perfect. No, they cannot be used as the future perfect, because they are not the future perfect. The word choice defines the tense, and you can't just call it something else. If you had written "I will have finished my homework," that would then be the future perfect.
No, forms like would, should, and could are not used to indicate the simple, unmarked future.
However, because they are fundamentally past-tense forms, they can be used to indicate the future in the past. Compare:
There is no need to bring the perfect aspect into this picture. It risks complicating things while in fact changing nothing.
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