Acronym said:
When I talked about the FUNCTION of the subject I meant that the subject does not mean the topic of the sentence nor the doer of the action.
For example:
Nothing worries these kids.
The subject is Nothing, and the topic is the Kids.
Also,
The apples were eaten by the bird.
Here the subject is The apples in which are not the action doer.
One thing more,
Into the room runs the dog.
The prepositional phrase, into the room, functions as the subject of the clause.
Thanks.
I wonder if you're mistranslating the names of the parts of speech from Arabic?
In,
"
Nothing worries these kids."
The subject is Nothing, and the topic is the Kids."
The subject of the sentence is "nothing", the verb is "worries" and the direct object is "kids."
There isn´t any reason why abstract nouns cannot function as a subject. The topic of the sentence is the "subject matter" or "theme" regarding the information content conveyed by the sentence.
In,
"The apples were eaten by the bird."
Apples is the subject, the conjugated verb is "were", used in the passive voice, hence the construction requires a past participle indicating the nature of the passive action, and finally "by the bird" is a prepositional phrase which specifies the agent of the passive action.
In,
"Into the room runs the dog."
The subject is dog, runs tells what the dog does, "into the room" is a prepositional phrase that tells where the dog runs. If we pare the sentence down to its absolute minimum, the sentence reads, The dog runs. "Into the room" has no function other than to tell WHERE the dog runs, and any word or phrase that tells HOW, WHERE, WHEN, has an adverbial function.
Although English speakers may intuit a preferred word order, as long as the necessary parts of speech are there (subject, conjugated verb at its simplest; object as well if the verb is transitive), word order may be flexible. Inversion of word order most often obeys certain wishes of the speaker to diverge from the norm, such as what happens with poetry.