Use commas to set off nonessential expressions--words, phrases, and clauses that are not necessary for the meaning or structure of the sentence.
You can tell whether an expression is nonessential by trying to omit it. If the sentence makes sense and is structurally correct, the expression is nonessential and should be set off by commas.
Examples
*Nonessential: Let´s talk to Bob, who has experience in this area.
*Essential: Let´s talk to someone who has experience in this area.
(1) * Use "did" to ask questions about the past. " ( "WH" word ) did + Subject + verb (base form)".
*** " WH" words are: when, where, why, what....
(2)* When you don't know the subject of the verb, ask the question directly with the verb in the past form without using "did". " Who/ What + the verb ( in the past )". Examples: (1)
Where did you go yesterday? When did she go? Did you have time to go to the party? (2)
* Use "very" when you want to intensify an adjective. * Use "so" when you want to show a cause and effect. * Use " too" when you want to express excess. ( always have an negative feeling )
Examples:
I was very tired when I arrived home. The joke was so good that I couldn't stop laughing. She was too late. She missed the whole class.
* Use "who"as an interrogative pronoun and in place of the subject of a question. It can also be used in statements, in place of the subject of a clause.
* Also use "whom" as an interrogative pronoun, but it is used in place of the object of a question. Therefore, "whom" can be used in statements, in place of the object of a clause.
* " Who" refers to people. "That," however, would not be incorrect in some sentence.
*"Which" & "that" refer to groups or things. Use "That" to introduce an essential clause, and use "which" to introduce a nonessential clauses, but if "this", "that", "these", or "those" has already introduced an essential clause, you may use "which" to introduce the next clause, whether it is essential or nonessential. Examples:
I don't see the guy that you said he was coming to meet us. ( Readers can't know which guy until they finish reading what comes after "that")
I'm reading the book, " 1984", which you recommended to me. ( Readers already know which book I'm talking about before reading what comes after "which" )
Those are the shoes which you've been looking for. That's the movie which I was talking about Notes :
*Essential clauses do not have commas surrounding them while nonessential clauses are surrounded by commas. * Often, you can write your sentence by leaving out "which" when"this", "that", "these", or "those" has already introduced an essential clause before.
Example: Those are the shoes which you've been looking for ....( better say).... Those are the shoes you've been looking for.
* "Say" is used with direct and indirect speech. Most often used without a personal object. If we want to put a personal object after say, we use "to".
Examples: She said that it was my last chance. She said that she would be late. (not She said me...) ...I say to all the people of this great country...
* "Tell": is used with direct and indirect speech. After tell, we usually mention the person being told. It's used to mean ‘instruct’ or ‘inform’. Also it is used to tell someone to do something.
Examples:
She told me that she would be late. She told me that it was my last chance. Tom’s mother told him to clean his room.
* "Talk": there's not very much difference between speak and talk.Talk is usually used to refer to conversational exchanges and informal communication.
Examples:
When she walked into the room everybody stopped talking. I'll talk to them tomorrow about this.
* "Speak": is often used for one-way communication and for exchanges in more serious or formal situations. It's also usually used to refer to knowledge and use of languages.
Examples
After she had finished reading the letter, nobody spoke a word. She speaks three languages fluently.