Eway said:
I don't understand tdol's reply. Does it mean they are both correct? "It has already past / passed the deadline."
If you want to express when or where, use 'past'. If you want to express the action of passing, used 'passed'.
The deadline has
passed. (Action; Participle)
The dealine has gone
past. (When; Adverb)
Hint, there can only be one main verb per sentence, so if 'has gone' is the main verb, then 'passed' wouldn't work. You need to use 'past':
*The deadline
has gone passed.
ungrammatical
The deadline
has gone past.
As for your example,
Main Verb is separated by 'already'
It
has already
passed the deadline. (Action; Participle)
As a main verb HAS means, possession:
*It
has already past the deadline. (When; Preposition)
But if the participle 'gone' is implied (i.e., understood but omitted by the speaker), then 'has' functions as part of the perfect verb 'has (gone)', and 'past' is the correct form to use:
It
has already (
gone) past the deadline.
Again, 'has (gone)' functions as the main verb, and since there can only be one main verb per sentence, 'passed' wouldn't work in that sentence. In other words, the sentence you've given us is ambiguous given that 'gone' could be implied: "It has already past/passed the deadline" carries two meanings:
It has already (gone) past the deadline. (grammatical)
It has already passed the deadline. (grammatical)
Try using the verb BE (is, are, was, etc.):
It
is already past the deadline. ('past' = When; Preposition)
Note, participles like 'passed' are not compatible with the verb BE, so in that case we know we need to use 'past'.
These are homophones undistinguishable in speech other than by use; in written English passed is always the past tense and past participle of the verb pass: I passed Spanish [another milestone, the final exam, a kidney stone]. Past is a noun (She pretends to a shady past), an adjective (That’s all past history), an adverb (Two fire engines went past), and a preposition (We stayed past midnight).