Correct spelling and grammar: J'ai l'impression que personne à Portsmouth ne se soucie de l'environnement (I have the impression that nobody in Portsmouth cares about the environment)
The sentence 'Les copains que j'ai sont ma vie' means The friends that I have are my life. The sentence 'Je les adore et je ne sais pas ce que je ferais sans eux' means I adore them and I don't know what I'd do without them. The sentence 'Mais il a trois personnes qui sont mes meilleurs copains' means But there are three people who are my best friends. The sentence 'Je mourrais sans eux' means I'd die without them. Nothing to improve here. The translation is perfectly accurate. Bravo!
It is the first sentence of a paragraph which is the topic sentence.
It in symmetry with sentence a is what? What is a sentence with symmetry in it? This sentence with symmetry is symmetry with sentence this.
Who or what the sentence is about is the subject of the sentence.
Who or what the sentence is about is the subject of the sentence.
The subject of a sentence is who or what that sentence is about.
yes
A subject in a sentence is who, what, or where the sentence is about.
the meaning of sentence is sentence
As a question, it can be a sentence, like: A sentence can have one word, and as a question then it can be a sentence: Who?
This is a sentence. A prisoner has to serve the sentence the judge gives him.
compound sentence, simple sentence, and complex sentence