(please correct me if you find mistakes in my writtings, i am trying to learn)
i have some questions regarding will have and would have. an example, 'By the end of the decade, scientists will have discovered a cure for influenza'.
1. in this sentence the part 'have discovered' is from present perfect tense and will is from simple future tense and it forms future perfect tense right?
2. is 'will have' together a modal auxiliary verb? if it is modal auxiliarry verb then how many modal auxiliary verbs are in this sentence?
3. another example-
It's half past five. Dad will have finished work by now and
It was half past five. Dad would have finished work.
in the first sentence i can tell that this is in future perfect tense but in the second tense is it in simple present tense? if it is simple present tense then how i will describe the part 'would have' there?
Sajid1234Dad will have finished work by now.
Dad would have finished work by now.
1) [will]modal auxiliary [have]perfect auxiliary [finished]main verb (past participle)
2) [would]modal auxiliary [have]perfect auxiliary [finished]main verb (past participle)
3) may have finished; must have finished; should have finished; ...
The verb phrases "will have finished" and "would have finished" in 1) and 2), and all such phrases as exemplified in 3) as well, are called modal perfect tenses — not simple present tenses. You can only have at most one modal verb in a clause, and it must be the first verb in the verb phrase.
Example 1) above has the special name 'future perfect tense'. Unfortunately, in English grammar the verb phrases in 2) and 3) have no special names. If you want to refer specifically to the verb tense in 2), say it's a "modal perfect tense with would".
(will have discovered follows the same logic. It also has the future perfect tense.)