What is the Place of Grammar in Language Teaching?

She read the letter which upset me.

This sentence indicates that a letter upset the speaker (me) and, that the same letter was also read by another person (she).

2. 
   She read the letter, which upset me.
   

This sentence indicates that the speaker (me) was upset that the letter was read by another person (she). In the second sentence a comma is used to divide the sentence and control the meaning, flow and rhythm. It also may provide a pause within the sentence; the use of a comma changes the pronunciation (stress, intonation etc.) and meaning of the sentence where a new meaning develops.

3. 
   He keeps his canary in the bathroom. This sentence indicates that ‘he’ keeps a certain object in the bathroom.
   
4. 
   He keeps his canary in the bathroom?
   

It may be a question asked by another person or a statement of surprise; ‘Really! The canary is kept in the bathroom by him! The first statement is a declarative statement that ends with a full stop. On the other hand, the second statement is an interrogative sentence that ends with a question mark (?), it might be a question asked by the speaker to receive an answer. The second statement may also be a rhetorical question that indicates the surprise of the speaker.
5. They went to Austria and Italy.
The sentences is spoken with a raising intonation, this statement of fact indicating the places they went to. Other people than the speaker went to the countries Austria and Italy.
6.They went to Austria and Italy...
The statement is spoken with a falling intonation towards the -the speaker is listing out the place they went to and the list is incomplete. This sentence also indicates that that other people than the speaker went to the countries Austria and Italy however, this sentence finishes with an ellipsis. The first statement is a declarative statement that ends with a full stop. On the other hand, the second statement uses an ellipsis (...); three dots used to show that words have been omitted from a quotation or to create a pause for effect. An ellipsis can be used: (a) to show an omission of a word or words (including whole sentences) from a text. (b) To create a pause for effect. (c) To show an unfinished thought. (d) To show a trail off into silence.