The convention is as follows:
Use the symbol ? to mark a semantically awkward sentence; e.g., ?I am a painting pause.
Use the symbol * to mark an ungrammatical sentence; e.g., *I like run.
 Peter is painting. <present continuous>
Let's test it Their food was gone. <past participle>
Adjective? painting Peter
Participle? Peter is doing something.
The present continuous takes the form BE + -ing
, also called a present participle. Delete BE and the -ing
becomes a nominal, either an adjective (also called a present participle) or a noun or a gerund. Word order is important here:
Present Continuous: I am swimming. <doing>
Gerund: Swimming is fun. <subject>
Adjective: She has a swimming suit. <modifier>
There are two kinds of participles, present (-ing) and past (-ed). They're named as such because their morphology is as such.
Past participles, as with present participles, can function as adjectives:
a viewing screen
Test: What kind of screen? A viewing one
a gone feeling
Test: What kind of feeling? A gone one
Adjectives can go either before or after the noun they modify:
Max is old ~ old Max
When the adjective comes after its noun, it's usually separated from its noun by a form of BE
, as in our example Max is old
Another way to test to see if the word after BE is a modifier or not is to use the equals sign (=):
Max = old <adjective>
('old' describes a characteristic of Max's)
Max = swimming <not an adjective>
('swimming' tells us what Max is doing; it doesn't describe a characteristic; unless, say, the -ing word describes him:
boring Max ~ Max is boring ~ Max = boring <adjective>
Here's another way to test to see how a past participle is functioning in a given sentence. Going back to our example  The food was gone
, notice the verb 'was'. It's in its past tense (e.g., is
: present; was
: past). There's this grammar rule that says there can be only one tense carrying verb per clause. In our clause above 'was' carries the tense, which means 'gone' can't be a verb; it has to be a past participle.
Let's test it
The food was gone ~ the food = gone
The word 'gone' modifies the 'food'. It describes it.
(On a side note, you could argue/say from a semantic point of view that 'gone' functions adverbially here:
is the food? It's not there; it's gone.)
In other words, there is more than one way to interpret a given utterance. Generally, though, especially when you're starting out, it's best to follow the basics.
Yes, pronouns are a subset of nouns. They refers to nouns; that is, instead of using a whole-big-long noun, you can use a little-small-short pronoun; e.g., Max was happy ~ He was happy. Pronouns are quite efficient.
Right, pronouns are not full nouns, so they cannot do as much as nouns.
Note the ellipsis in silly [for] me. Drop 'for' and the resulting form appears to be modified by an adjective. Not so. That's just what we see/read and hear; It's not it's real or underlying representation. That is, in language, any given utterance has two realizations, the one we see/read and hear, and the one our wetware/brain processes.
When analyzing a phrase or sentence that you know is grammatical, yet doesn't fit the rules of the grammar, look for what's not there. You'll find that ellipsis, the omission of words, even phrases, is at play and having fun. The reason there's so much ellipsis is that language is the more preferred when it is more efficient. Which is why speakers will and do drop words and phrases now and then.