We talked about the boy with a gun from the countryside.
PP Phrases add information to nouns or verbs, but if there is more than one noun in a clause,
Does it cause ambiguity?
Like the example sentence above(may be kind of silly),
is it the boy that is from the countryside or is it the gun that is from the countryside?
The world of turmoil in China.
Same question here, of turmoil will obvioulsy describe world,
but what about the PP in China,does it describe turmoil or the world?
English sentences can often be ambiguous. Your first sentence has more ambiguity than just that - was it the boy who was "with a gun", or did they talk "with a gun"? In that case, it's reasonably obvious which it is. A lot of ambiguity is resolved with semantics - only some interpretations make sense - or with context - other sentences nearby make it clear which interpretation is intended.
It's hard to completely avoid grammatical ambiguity. Sometimes you can do it with a rephrase, or with commas to make it clear that there's a relatively self-contained phrase. Sometimes picking alternative words or structures will do it, and sometimes re-ordering the sentence is best. For example, your first sentence could be:
They talked with a gun about the boy from the countryside.
They talked about the boy from the countryside, who had a gun.
They talked about the boy, who had a gun from the countryside.
Your second sentence could be parsed as "the (world of turmoil) (in China)", where whatever turmoil is very significant, as in the idiom world of hurt. It could also be parsed as "the world (of turmoil in China)". Any rephrase to clarify to that would likely be wordy, but it's likely that context around the sentence will be able to make it clear.
Can they be ambiguous? Absolutely. The longer and more complicated the sentence, the greater the chance. So it is down to the writer or speaker to make sure they exclude any ambiguity.
Usually context makes it clear. Any ambiguity in your sentences is essentially cleared up by context. Why would anyone mention where the gun is from? It's unlikely to be that. World of turmoil is a phrase by itself, so really "in China" refers to the whole phrase.
But ambiguity happens all the time, often with humorous effect.
Please do not bring plastic bin bags to wear. We’ve had runners tripping over them, and they just end up in landfill.
Cameron Diaz encourages women to keep their pubic hair in her new book.
A local man was fined on Monday for repeated trespassing and criminal damage. Margaret River Magistrates Court heard how the man entered a local school building by forcing open a window with another man.
These are all real quotations where ambiguity ends up creating some unexpected results.
