means shortening it to a phrase.
So to reduce an adverb clause of time,
we need a time word and a present participle.
That's the -ing form of the verb.
The present participle has an active meaning,
so it's understood that the subject is doing the action.
We can only form a phrase from an adverb clause
if the subjects of the two clauses are the same.
Who began to have strange dreams? I did.
That's why we can use this phrase.
Can the adverb clause be reduced to a phrase?
No. The subjects are different.
Here's how you make an adverb clause a phrase.
And remember with that present participle
you're expressing an active meaning.
We don't always use a time word
when we shorten an adverb clause of time.
While is often omitted because it's understood.
Hopefully, you understand how I wrote this sentence in the story.
Let me point out that the full adverb clause
could be written a different way.
After "while" there could be a progressive verb:
"While two children were sleeping..."
Again, the process would be the same.
- in this case a form of BE.
And our main verb is already a present participle.
When we change adverb clauses with progressive verbs,
and keep the present participle.
I mentioned that we often omit "while"
We sometimes omit "when," too.
When is understood, so I left it out.
but in more formal English I could have written:
"Upon" is a time word that has the meaning of "when."
Let's talk for a moment about word order.
These phrases that act like adverbs
are usually in an initial position.
At the beginning of a sentence.
But they can also be in a final position.
Here are two lines from the story.
In both sentences, the phrase comes before the main clause.
Commas are generally used for separation.
Now compare those examples to these.
I have two more lines from the story.
In these two sentences, the phrase comes after the main clause.
Commas aren't always used for separation in this case.
In the first sentence, I chose not to use a comma.
In the second, we have a longer phrase.
Most writers would use a comma here.
It helps the reader to separate the two ideas.
I'd like you to try a very short exercise to test your understanding.