It is Friday finallfinally Friday. It is finally Friday.

I am very happy to have a weekend without working. I am very happy to have a weekend without work.

Technically correct, although the nominalization of the verb "work" here is a little unnatural as "work" is also already a noun. Of course there are circumstances where the noun "working" is used, there is a difference in nuance to look out for. Pay attention for that next time you're reading or listening to something in English.

I am very happy to have a weekend without working. I am very happy to have a weekend without work.

It is 10 p.m. now, and I am very tired and drowsy. It is 10 p.m. now, and I am very tired and drowsy.

correct, but redundant, "tired" and "drowsy" mean the same thing

It is 10 p.m. now, and I am very tired and drowsy. It is 10 p.m. now, and I am very tired.

One of my students told me that he wants to change a teacher in charge of class, because I was so strict with them. One of my students told me that he wants to change teachers, because I was so strict with them.

In a "one of" noun phrase, the plural is used for the noun you are modifying. "Change (plural noun)" is a common phrase as well as the grammatically correct way to say it, instead of using the singular. The "in charge of class" part is just a little redundant, maybe.

One of my students told me that he want to changve a teacher in charge of class,different teacher because I was so strict with them. One of my students told me that he want to have a different teacher because I was so strict with them.

He compared me withto other teachers and pointed out that when they made mistakes in dictation, I punished them too hard. He compared me to other teachers and pointed out that when they made mistakes in dictation, I punished them too hard.

He compared me with other teachers and pointed out that when they made mistakes in dictation, I punished them too hardshly. He compared me with other teachers and pointed out that when they made mistakes in dictation, I punished them too harshly.

I told him that I was so glad he had such a great idea likeand that and I hoped he would take actions right now. I told him that I was so glad he had such a great idea and that I hoped he would take action right now.

I also would do him a favor to get connection with the head master. I also would do him a favor to get connection with the headmaster.

"Headmaster" is one word.

I also would also do him a favor toand get connectionhim in touch with the head master. I would also do him a favor and get him in touch with the headmaster.

He said that I wanted to go on strike. He said that I wanted to go on strike.

I told him that I wasdidn't. I told him that I didn't.

Connect with the previous sentence: "He said that I wanted to go on strike, but I told him that I didn't."

All I wanted was inmproved improper to be a teacher. All I wanted was improved improper to be a teacher.

Don't quite understand what you mean here

He told me that he wouldn't do that because of my hard work, onlyjust if I wouldidn't treat them badly. He told me that he wouldn't do that because of my hard work, just if I didn't treat them badly.

How I wanted to make a program tofor him and asked him do it immediately. I wanted to make a program for him and ask him do it immediately.

Starting with "how" could be technically correct but not easy to pull off in writing

I wanted to be free from the job, which was really was a hard work with a low salary. I wanted to be free from the job, which was really hard work with a low salary.

"work" is a plural noun

I wanted to be free from theis job, which really was a hard workjob with a low salary. I wanted to be free from this job, which really was a hard job with a low salary.

Alternative to the other correction

I wanted to spend more time studying German and English. I wanted to spend more time studying German and English.

I wanted to spend more time studying German and English instead. I wanted to spend more time studying German and English instead.