Chapter I: the pecularities of formal and informal language

She is not is contracted to she isn’t or she’s not. I am not is only contracted to I’m not. Not: I’m n’t or I am n’t. They are not is contracted to they aren’t or they’re not. The isn’t / aren’t contractions are more common after nouns. The ’s / ’re not contractions are more common after pronouns: The cakes aren’tready yet. She’s not a friend of mine.
Other contractions
Contractions can occur after nouns, names, here, there and now and question words. These contractions are not considered appropriate in formal language:

My sister’s got married.	=	My sister has got married.
John’ll be very happy.	=	John will be very happy.
Here’s the coffee.	=	Here is the coffee.
There’s your watch.	=	There is your watch.
Now’s your chance.	=	Now is your chance.
Where’s the milk?	=	Where is the milk?
What’s happened?	=	What has happened?

3. 
   Relative structure. We can use relative structure in formal language. For example, The woman thought that it was important to be on time. However, relative structure is not used in informal language. For example,,The woman thought it was important to be on time”.
   
4. 
   Passive structure. There are numerous people who use always passive structure in their formal language. It uses more indirect language, making it less personal. For example,, The student was given a book”. Otherwise, we can not use passive structure in informal language. ,,We gave the student a book”
   
5. 
   Auxiliary verb usage. Always use of full form of auxiliary verb in formal language. For example,, Have you finished your work? Sometimes the auxiliary verb is dropped in informal speech. This is often grammatically incorrect, but is certainly common in everyday usage. For example,, Finished your work”?
   
6. 
   Ellipsis. We should not use ellipsis in formal language, but it is common to use ellipsis in informal language. For example,
   

1. 
   We went to the Barcelona for the weekend. We have a lot of things to tell you (in formal language)
   
2. 
   Went to the Barcelona for the weekend. Lots to tell you.(in informal language)
   

7. 
   Personal pronounces. We mostly use third person in formal speech, but we may use any kind of personal pronounces in informal speech. For example, Bahrom, Aziz, they, them are in formal speech. I, he, she, it, you, they, Aziza are in informal speech.
   
8. 
   Modal usage. We should choose modal verbs according to the structure of the sentence. For example,
   
   1. 
      Can I suggest you try this new model(neutral)
      
   2. 
      May I suggest you try this new model( formal)
      
   3. 
      Might I suggest you try this new model( very formal)