Exercise

1) My dog is looks so cozy when I arrived get home from work.
2) Since I haven't I'd not slept a lot in these days, probably I could will slumber today.
3) He's funny and he has a lot of wit.  (or: He's funny and very witty.)
4) My dog will bark very loudly when you will arrive.
5) Tomorrow will be the an important day for me and my peers because we will have to stand up in front of our chairman.
6) The teacher was so blunt when he said that my marks are bad.
7) I'm willing to help for the marriage but must looking for someone to cater. (?）
8) I notice that my boots do make some noise when I scrub slide them on the floor.
9) My sister bothers me when she dances.
10) I rely on my girlfriend because she is faithful. (or: I trust my girlfriend ...)

Exercise

1) My dog was so cozy when I arrived from work. (or "When I arrived from work, my dog was so cozy.")
2) I'd not As I hadn't slept a lot in these during those days, probably I could slumber I could probably sleep today.
3) He's funny and (*he) has a lot of wit. (*Repeating the pronoun depends on whether you are using British or American English.) 
4) My dog will bark really loudly when you will arrive. (When you arrive, my dog will bark very loudly - really changed from very because loudly is an adverb modifying really - the -ly ending)
5) Tomorrow will be the an important day for me and my peer because we will have to stand up in front of our chairman.
6) The teacher was so blunt when he said that my marks are were bad.
7) I'm willing to help out for with the marriage but must looking look for someone to cater.
8) I notice that my boots do make some noise noises/a noise when I scrub them on the floor.
9) My sister bothers me when she dances.
10) I rely on my girlfriend because she is faithful.

Very well writtern overall!