I forgot to include these 5 statements I still have doubts about. Thank you.
1) Since George Orwell was a child, he developed an independent-minded personality and then he professed (?) atheism and socialism.
2) He didn't accept the strict discipline imposed at Eton since it implied the use of corporal punishment.
3) The greater (better : greatest) part of American slaves lived in the USA. The Northern gathered themselves in (into?) the Republican Party.
4)The Ministry of Truth was a pyramidal structure were the three slogans of the Party were written (??)
5) You should have referred to th episodes which led to the abolition of slavery instead of dwelling on living and working conditions of the slaves.
3 seems strange. Actually ALL the American slaves lived in the USA. Also, I don't know what you mean by "The Northern" -- the northern what?
4 - the first "were" should be "where"
5 - the, not th