While “ability” refers to actual and existing skill or aptitude that may be either innate or acquired, “capacity” in the context of skill relates to the innate characteristic of being able to develop something. “Capability” is similar, but it can be acquired. The word has a few slightly different meanings, the most distinctive of which is “a unique readiness to accomplish a specified objective.” In this regard, it demonstrates its "yes or no" nature while also expressing potential.


“Ability,” “capacity,” 
And “capability”
May all to skill or aptitude
Refer with certainty.

Though in this mode, “capacity”
A prospect will imply,
Capacity is true innate,
Not made there on the fly.
 
Alike is “capability”;
Potential “p” it shares.
But native state it need need not be;
It often late appears.

And “capability” as well 
Is either yes or no.
It's not a matter of degree,
Worked up or native so.

“Ability” though as we know,
Means actual skill on tap;
The glass one gets may partial be,
Or brimming at the top.

There was a time “ability”
Was animate-object bound.
Those days had simpler rules perhaps,
With clearer answers found.

When putting “capability”
Where was “ability,” 
Decide if measure's “yes or no”
Or if degree it be.

​

Although the word “except” apparently originated as a verb, it is most commonly used as a conjunction or a preposition nowadays. Its listed meanings as a conjunction include “only,“ “under any other condition than,“ and “with the exception of.” As a preposition, it may indicate “not including,” “but not,” and “other than.” It is when it functions as a conjunction, often taking the place of the coordinating conjunction “but,” that it requires a comma, which alerts the reader to the beginning of a new idea that can almost, if not entirely, stand on its own. Sometimes “except” is used to introduce a parenthetical statement (i.e., information that could be put in parentheses since nonessential). Such parenthetical  information is set apart by two commas if in the middle of a sentence.


Apart from use as verb “omit,”
“Except” is typed as one of two.
Conjunction may it be when writ
Or preposition if more true.

Its meaning when in latter role 
Is “not including,” “other than,”
“But not,” or other such by soul;
Perhaps more stout in kindred stance.

Conjunctions join distinct ideas,
Not simple noun to single word.
“Except” when serving thus most days
Will boast a comma, strength assert.

Between two independent parts
Or adding on dependent clause,
Like parentheticals apart,
It sports the comma, marks its cause.

“The trees are mainly thick and green,
Except they thin along the cliff.”
“The rushing wind will howl and keen, 
Except when not so very stiff.” 

The case of parentheticals
Is easily seen and commonly known:
“Some tools, except mechanical,
Were hung on pegs as if there flown.”

If prepositional is the use,
No comma stands to tout the event.
Except at start of sentence news, 
It quiet comes, no notice sent.

“The meeting had already begun 
When cautiously he took a peek.
He knew he had to get it done;
The door was safe except for squeak.”

The key for commas with “except”
Boils down to knowing part of speech.
Put parentheticals aside,
And spot conjunctive usage each.
​

​That proof is in the pudding
Is proven after oven;
But “oven” within “proven”
Is proved by simple vision.

So here we see that “proven”
Is participle likewise
To “proved” in sentence given;
No doubt a cause of sad sighs.

For often it is questioned
Why these two words should battle
To prove the most deserving
To serve as only participle.

It leaves us quite unsettled
When choosing “proved” or “proven”:
What rule “has proved” its truth yet 
Or what “has proven” certain.

Though use by country varies,
Feel safe with “proved” in general.
It ends in “d” deliberate,
“Default” the clue in total.

For adjective, no quandary;
It's “proven,” recent risen.
Remember “proved” is also
The simple past when bidden.

Once extinguished, then extinct;
Yet a flame may live again.
Once distinguished, then distinct;
Yet such fame may need refrain.

Once extinct, no chance extant;
Not there standing evermore.
For “extinct,” no small extent;
Full its measure, ever sure.

If extant, beware extent
Though of life rejoicing be.
Coming end may some resent,
If indeed that's all they see.

​

​Since “later,” “after,’ “then,” and “next”
Are one-word adverbs of time, 
Like “subsequently,” “afterward,”
They live by rules sublime.

Conjunctive adverbs joining thoughts
Expressed as clauses, more,
Must bow with every entrance made,
Give clue to function sure.

The comma brought along is clue
Of clause-wide role ahead
To modify the thought to come
While linking that which led.

A sentence here may illustrate
This role so commonly seen: 
“We'll have to let the fruit get ripe;
Indeed, it's still too green.”

But “then” is special like its peers,
The one-word temporal ones:
“They pranced and danced and lost their pants;
Then all fell down at once.”

Among conjunctive adverbs all,
These words when functioning thus
Are not required a comma to show
But strut with status plus.

The regular adverbs similar are,
For different reason though.
No comma  cometh in between
Such adverb and its bro'.