Only verb can be in past tense or even adjective can be in past tense?
Correct.
In the above sentence "desolated" is a verb or an adjective? My guess is it's an adjective here.
Desolated is certainly an adjective in your sentence.
Is "desolated" a past participle of the verb "desolate"?
Yes it is. And as so many past participles, it can be used as an adjective. The street could also have been deserted, darkened, emptied, forgotten or populated. All past participles that can be used in this sentence as adjectives.
Is the above sentence wrong and should I have written the above as below?
No, it is just fine as you wrote it.
However, desolate on its own, can also be used as an adjective. And this is where the confusion starts.
There seems to be a nuance difference between desolate and desolated.
If you use desolated, you indicate that the state of the street is the effect of it having been desolated - or you could say ruined.
If you use desolate, it feels more as if you describe an overall attribute of the street, that might be comparable to it having been desolated, even if it has always been like that - a more apt synonym could be bleak in that case.
Thought-provoking question!
I think we need to look at the sentence structure or else it'll be difficult to find it out. While transitive verbs make our task easy as they'd have a direct object following them. the problem occurs when the verb is intransitive.
But then, if you use 'intransitive' verbs, the sentence won't look complete without explaining the verb. For instance, 'break' is transitive and intransitive both (just like 'clean'); now you'll have to talk about the verb further in order to make the sentence complete.
He has broken - won't work
The moment you add '....his glass', we can make out that it is used as a verb.
The adjective pattern will be different than the 'verb pattern' in those sentences with PP.
In English, a 'single word' on its own may stand ambiguous. That's why we say, context is important.
[But let natives come with their take on this].
Best Answer
The verb in the example is "to paint". The principle parts of this verb are "paint", "painted" and "painted". The second and third principle parts happen to be the same, as they are for most English verbs.
However, that similarity does not occur in every English verb. For example, the principle parts of "to take" are "take", "took", "taken".
This sentence uses the second principle part -- the past tense form. The word is used as a verb, has a tense, and has no auxiliary.
This sentence uses the third principle part -- the participle form. The word is used as part of a complete verb that includes the auxiliary "has". The complete verb is in the present tense and the perfect aspect.
The version that uses the verb "to take" cannot be mistaken for the past tense form -- "taken" looks and sounds nothing like "took". For the version that uses "to paint", it is only the fact that there is an auxiliary verb that indicates "painted" is the participle form.
By the way, this is not a passive voice construction. Passive voice uses the auxiliary "to be" instead of "to have". For example, "the picture was taken" or "the picture will be painted".
Participles can be used as a part of a complete verb, but they can also be used as modifiers. When they are modifiers, they are not combined with auxiliaries.
In general, participles that are alone come before the noun, as in "the painted picture". Participial phrases, however, tend to follow the noun:
The phrase "painted by Karen" does not have a tense, does not form a predicate, and does not have a subject. Instead, it behaves like an adjective and answers the question "which picture?" There is a verb in this sentence, but that verb is "is". The subject of "is" is "picture".
Prepositional phrases can do the same sort of job. Consider:
The picture of three apples is now in a museum.
Your comment includes an example sentence that has bad grammar:
Here's the problem: "Was painted" is a complete verb. It has a tense, it forms a predicate, and it needs a subject. "Is" is also a complete verb, possessing tense and forming a predicate and needing a subject. Unfortunately, there's only one subject available, and it can't satisfy both predicates.
There are a few ways to fix that problem. One way is to remove "was" and let "painted by Karen" act as a modifier. Another way is to give "was painted by Karen" its own subject, such as "The picture that was painted by Karen is now in a museum." Yet another way is to join the two predicates with a conjunction, so that the one subject can satisfy the resulting compound: "The picture was painted by Karen and is now in a museum."