Can you please help me check these sentences, please? Thank you.

1) Slaves were considered as animals: white slaves used to sell them by auction.
2) Furthermore, white slave owners imposed a system of punishment and reward (better: of punishments and rewards to keep the slaves under control).
3) Additionally, slaves were forced to reject their tradition.
4) Anyway, despite (Though) they had hard and painful lives, they weren't miserable all the time: they were allowed to sing and dance; in this way thy got used to singing soaring and haunting songs.
5) Smith's life (better the life of Winston Smith) appears monotonous ad melancholy, because deprived of any form of privacy and relationship with other people.
6)(The) big brother is always watching his movements and listening to all the words or whispers he makes through the telescreens that are placed all around the city and thanks to the Psycho Police that spies all the citizens in their everyday life.
7) Furthermore, another element that provides to show the miserability of his life (that stresses his miserableness) is his physical aspect: he looks small, frail and skinny and appears even smaller and frailer in the blue overalls of the Party.
8) In addition, is skin, that should have been pink, had turned red because of the coarse soap and the old blunt razor blades which even roughened it (which had roughned it?).

1) Slaves were treated like animals: white slavers used to sell them by auction.

2) Furthermore, white slave owners imposed a system of punishment and reward to keep the slaves under control.

3) Additionally, slaves were forced to reject their own cultures and traditions.

4) Although they had hard and painful lives, they weren't miserable all the time: They were allowed to sing and dance, and they learned to sing soaring and haunting songs. [I'm wondering what is meant by the last part of this sentence. Be sure to read ** at the bottom of this message.]

5) The life of Winston Smith appears monotonous and melancholy because he was deprived of any form of privacy and relationship with other people.

6) Big brother is always watching his movements and listening to all his words or whispers through the telescreens that are placed all around the city and thanks to the Psycho Police that spies on all the citizens in their everyday lives.

7) Furthermore, another element that shows the misery of his life is his physical aspect: He looks small, frail, and skinny and appears even smaller and frailer in the blue overalls of the Party. [After a colon, use a capital letter if there is a complete sentence following or a lower-case letter if there is not a complete sentence following.]

8) In addition, his skin had turned red because of the coarse soap and the old blunt razor blades which had roughened it.

**from http://www.negrospirituals.com/ --
But some “drivers” also allowed slaves to sing “quiet” songs, if they were not apparently against slaveholders. Such songs could be sung either by only one soloist or by several slaves. They were used for expressing personal feeling and for cheering one another. So, even at work, slaves could sing “secret messages”. This was the case of negro spirituals, which were sung at church, in meetings, at work and at home.

The meaning of these songs was most often covert. Therefore, only Christian slaves understood them, and even when ordinary words were used, they reflected personal relationship between the slave singer and God.

The codes of the first negro spirituals are often related with an escape to a free country. For example, a “home” is a safe place where everyone can live free. So, a “home” can mean Heaven, but it covertly means a sweet and free country, a haven for slaves.

Sure! I can help you check these sentences. Here are the suggested revisions:

1) Slaves were considered as animals. White slave owners used to sell them by auction.
2) Furthermore, white slave owners imposed a system of punishments and rewards to keep the slaves under control.
3) Additionally, slaves were forced to reject their traditions.
4) Despite leading hard and painful lives, slaves weren't miserable all the time. They were allowed to sing and dance, which helped them get used to singing soaring and haunting songs.
5) The life of Winston Smith appears monotonous and melancholy, deprived of any form of privacy and relationships with other people.
6) Big Brother is always watching his movements and listening to all the words or whispers he makes through the telescreens placed all around the city. The Psycho Police spies on all citizens in their everyday life.
7) Additionally, another element that emphasizes the misery of his life is his physical appearance. He looks small, frail, and skinny, and appears even smaller and frailer in the blue overalls of the Party.
8) In addition, his skin, which should have been pink, had turned red because of the coarse soap and the old blunt razor blades that had roughened it.

These revisions clarify the meaning of the sentences and improve the overall flow and grammar.