"The boy runs in the park every morning." Present Tense
The boy is running in the park."
"The boy in the park is running".: both Present Progressive Tense
"The boy in the park is running." I'm not talking about the boy in the street, or the boy in the school yard. I am talking about the boy who is in the park.
"The boy is running."
Where is he running? In the house? In the school corridor?
"No. The boy is running in the park."
Can you see how this difference is the same for "The boy in the house kills the dog." and "The boy kills the dog in the house" ?
I am very confused how to use adj or adv, especially preposition phrase functioning as adj or adv.
I see adj modifies noun, and adv modifies the others (e.g. verb, adjective,...).
PM: Basic error! PPs do not function as adjectives or adverbs, but as modifiers or complements, and occasionally as subjects. Noun, verb, preposition, adjective, adverb etc., are word categories (parts of speech), whereas functions are subject, predicate, modifier, complement etc. Correctly distinguishing category and function is crucial to understanding English grammar.
Josh
For example:
The boy in the park is running.
In my thinking, the sentence also tell me running occurs in the park.
So what is the difference between "The boy in the park is running." and "The boy is running in the park."
PM: It's all about which element in the sentence is being modified. In The boy in the park is running, the underlined PP is postmodifying the noun "boy". The NP "the boy in the park" identifies which boy is running.
By contrast, in The boy is running in the park, the PP is an adjunct modifying the verb "running". It tells us where the running is occurring.
Josh
For example:
The boy in the house kills the dog.
In my thinking, "in the house" and "killing" occurs at the same moment.
So what is the difference between "The boy in the house kills the dog." and "The boy kills the dog in the house."
PM: Preliminary point: In The boy in the house kills the dog the PP "in the house" is not an occurrence, but a stative situation. It has no direct bearing on any dynamic situation expressed in the sentence other than to express the location of the actor involved in the action.
Again, it's all about which element is being modified. In The boy in the house kills the dog the PP is a postmodifier of "boy". The NP "the boy in the house" identifies who kills the dog.
On the other hand, in The boy kills the dog in the house, the PP "in the house" is an adjunct modifying "kills". It tells us where the killing occurs.
Josh
For example:
If I want to describe something in a dark place now, and it can look good in a light place.
Could I say:
Something in the dark place looks good in the light place.
I feels unnatural, but I don't know why it is so strange.
PM: You’re right, it is totally unnatural. Without more context, it is difficult to recast it, but a more likely possibility might be The x in the dark place would also look good in a light place.