ref – https://www.esu.edu/writing-studio/guides/participles.cfm

Initially we mentioned present participles in Present Continuous, where the participle is used to represent the main verb and we had a helping verb to help express the tense.

I(subj) am (helping verb) working (main verb) on a project.
They(subj) are (helping verb) eating (main verb) fried chicken.
She(subj) is (helping verb) sleeping (main verb) on (prep) the sofa (obj).

But let’s look at participles more in detail:

Present Participles act as:

Adjectives

• The running water tastes fresh.
• I know a pond teeming with fish.
• The smiling child waved at us.

(As nonessential (没必要) information modifying a noun) (non-restrictive Participle phrase)

• Delores, walking along the shoreline, noticed her cousin.
• The old house, creaking with every gust of wind, stood on the hilltop.
• The dancer, twirling gracefully across the stage, captivated the audience.

As nonessential (没必要) information modifying independent sentences

If the nonessential (没必要) element is at the end of the sentence, you need a comma in front. These commas are called “only” commas because they are used when only one thing can be referred to (one person, one type, one item), thus rendering the specifier within the commas nonessential.

• He ran carrying two plates of food.

  ran is the main verb.
  He ran, carrying two plates of food.

• The warrior jumps (into battle), [swinging an ax].

  The warrior jumps into battle is an independent sentence.
  swinging an ax is called nonessential information. We add it to be more descriptive.
  Hence, we must add a comma between the independent sentence and our nonessential information.

  • The warrior jumps into the [unwavering] battle. (present participle as adjective)
  • The warrior notices the battle [ending abruptly]. (present participle phrase modifies object ‘battle’ as adjective)

• I stood staring at the sunset.

  stood is the main verb.

  I stood, staring at the sunset

• In these examples –
  independent sentence, [nonessential information]:

  She walked away, [whistling a tune].
  She walked out of the room, [slamming the door behind her].
  He left the room, [whistling a tune].
  She walked down the street, [smiling happily].

Fronted Participle Phrase – Modify entire sentences (as a sentence adverb)

Time: [Finishing his homework], he went out to play.
Reason or cause: [Feeling tired], she decided to go to bed early.
Condition: [Weather permitting], we will have a picnic tomorrow.
Manner: [Smiling broadly], she accepted the award.
Concession: [Admitting his mistake], he apologized sincerely.

[Laughing hysterically], the children ran around the playground.

Forming part of a verb phrase:

Present Continuous:
subj + [is/am/are/..etc] + verb+ing + [complements]

Examples:

They are (helping verb) playing (main verb) in the park.
She is (helping verb) helping (main verb) with the dishes.
I am (helping verb) having (main verb) the time of my life.

Participles vs Gerunds

• Present Participle usage: He ran, carrying two plates of food.

  ran is main verb
  “carrying” describes an action happening simultaneously with ‘run’.

  Gerund usage: Carrying luggage is hard work.
  ‘Carrying’ is used as a noun, in the subject position.

• Present Participle usage: The warrior jumps into battle, swinging a mighty ax.

  jump is main verb
  “swinging a mighty ax” (挥hui1 舞着）is nonessential information that modifies the sentence “The warrior jumps into battle”.

  Gerund usage: The warrior likes [swinging axes].
  swinging is a gerund. “swinging axes” is a gerund phrase acting as the direct object of the verb “like”. It functions as a noun.

• Present Participle usage: I stood, looking at the sky.

  stood is the main verb
  “looking at the sky” is nonessential information.

  Gerund usage:

  [Looking at the sky] is my favorite pastime.
  “looking” is the subject of the sentence, and functions as noun.

  “Looking at the sky” is a gerund phrase and acts as the subject of the sentence.

Sample Story

Participle Practice (1-5):

A tiger appears [waving its tail]. // no distance, no comma needed

It roars (out loud), [baring its teeth]. // distance, so we need a comma

He notices a bunch of chickens [strutting around]. // as adjectives to describe ‘chickens’

[Crouching comfortably], the tiger waits to pounce.

The chickens, [being clueless], stares into the tiger’s hot dark mouth.

A turtle lives in a [soothing] forest. (modifies forest as adjective)

His name is Ted.

Ted jumps (into a cool pond), [paddling his flippers]. // nonessential info ‘paddling…’

He swims in the cool water.

He resurfaces, [kicking frantically with his short stubby flippers]. // nonessential info ‘kicking…’

Ted sees a group of birds [landing on a tree branch]. (“landing on a tree branch” modifies birds as an adjective)