1 2
Quash me if I am wrong, Mike, but doesn't "suddenly" ... The addition of "suddenly" tells us when he "felt afraid."

It's a poorly written sentence. As it is written, the implication is that one can feel "suddenly afraid". I don't know how that could happen.

Maybe you're bolder than the rest of us.
I would expect that the person "suddenly felt" afraid, as that makes a lot more sense. The "suddenly" then does indeed apply to the "feel".

I think the two sentences have different nuances and are both good English.
However, I don't think you can write "*He felt slowly afraid" but "He slowly felt afraid", though a little odd, would be possible.

Zen
Many verbs take an adjective complement: He was afraid. He felt afraid. He felt happy. He called me stupid.

And when they do, we call them linking verbs. 'To be' is a linking verb as are many others which can be replaced by 'to be'. The adjective complements (further describes) the noun 'cloth', not the verb, so it's an adjective. Some other common verbs which can be used as linking verbs are: feel, look, smell, sound, taste, appear, seem, become.
The cloth looks blue.
The cloth is blue.
The cloth feels rough.
The cloth is rough.
Diane
Teachers: We supply a list of EFL job vacancies
Thank you, Dr. for your applying your keen reason to grammar.

He was not afraid, but something happened and in an ... The addition of "suddenly" tells us when he "felt afraid."

If you write "suddenly felt afraid". This could mean that the source of fear had existed for some time, but ... the suddenness of the fear. It strongly implies that the source of the fear has not existed for some time.

This made sense to me, and I understand the concept about where fear is on the existence level, but it set me off in language la-la land, trying to work it out.

'This is beautifully put.'
I wrapped my mind around the concept, the subtly expressed in 'feeling suddenly afraid.'
I applied the logic to the sentence 'This is beautifully put.' When you wrote that paragraph, which I conceived as 'beautifully put', 'this' (the nound phrase) came into existence 'is' being the main verb, the main verb of the verb phrase 'is beautifully put', and a verb phrase in itself.

Dividing that prase, 'beautifully put' modifies that main verb 'is', functioning as an adverbially phrase. Structurally then, 'beautifully' modifies 'put.' So, he 'felt suddenly afraid,' I get it, but then . . .

Does that mean then that the source of 'this,' which I conceived as 'beautifully put,' did not have the qualities of beauty until it came to be?

or
that 'this' had the qualities of beauty all along but never had existence before? Huh?
'Something that does not exist, cannot be beautiful, can it?' I ask myself. Hmmm . . .
If an adverbial phrase modifies a verb phrase, how does an adverb modify a secondary verb? I see the answer. It is a matter of logic.

But, wait, isn't 'beautifully put' also functioning like an adjective in the sentence?
('This is .' Noun verb adjective.)
mm pwuah

Susan
However, I don't think you can write "*He felt slowly afraid" but "He slowly felt afraid", though a little odd, would be possible. Zen

You could write, 'He felt increasingly afraid.' Is that odd?

Susan
Many verbs take an adjective complement: He was afraid. He felt afraid. He felt happy. He called me stupid.

And when they do, we call them linking verbs. 'To be' is a linking verbas are many others which can ... appear, seem, become. The cloth looks blue. The cloth is blue. The cloth feels rough. The cloth is rough. Diane

Now if we add an adverb to each of the above, we have structures similar to 'He felt suddenly afraid.'
Try it. It ain't that easy.
I think I will go with a structural rule on this one breaking the sentence down into parts until you end up with 'suddenly' modifying 'afraid'. 'Suddenly afraid' is an adjectival phrase, consisting of a verb and an adverb.
When I try to reason out the intention of meaning, everything gets muddled.

I don't know how we are supposed to understand whether the source of fear
1)came at the instant he felt afraid

or
2) was there all along, but he suddenly felt it

from
'He felt suddenly afraid.'
To truly understand what the sentence means, ya gotta hava context, no?

Susan
Students: We have free audio pronunciation exercises.

However, I don't think you can write "*He felt slowly afraid" but "He slowly felt afraid", though a little odd, would be possible. Zen

You could write, 'He felt increasingly afraid.' Is that odd?

It sounds ok to me.

Mike Nitabach

However, I don't think you can write "*He felt slowly afraid" but "He slowly felt afraid", though a little odd, would be possible. Zen

You could write, 'He felt increasingly afraid.' Is that odd?

No, it's fine. But what's increasing, the feeling or the fear?

Zen
married,

If you write "suddenly felt afraid". This could mean that ... source of the fear has not existed for some time.

'This is beautifully put.' I wrapped my mind around the concept, the subtly expressed in 'feeling suddenly afraid.' I applied ... put' also functioning like an adjective in the sentence? ('This is .' Noun verb adjective.) mm pwuah

I think you might be thinking too much about it.
In "it is put", "put" is an adjective. It describes what "it" is (it is in the state that results from the completed action of putting).

In "it is beautifully put", "beautifully" is an adverb describing the adjective "put". There is no "adverbial phrase" but there is an adjectival phrase, if you want to call it that.
As you correctly note, "I am suddenly afraid" is structurally the same.
What am I? I am afraid. What type of afraid am I? I am suddenly afraid. That's how we learned to parse sentences like that in primary school!
In "This is beautifully put", you are describing "this". What is "this"? It is "put". What type of "put" is it? Beautifully put.

It isn't beautiful. It is put. Do you see?
Zen
Students: Are you brave enough to let our tutors analyse your pronunciation?
That's true of nearly all sentences but doesn't necessarily, or even often, change what they can mean as a consequence of their structure.
Zen