*Form:
I + am + v-----ing.
He/she/it + is +v----ing
We /you/they + are +v-----ing
EX: I am reading a story now
EX: He is sleeping at the moment
EX:Look!They are running.
Note:
-If the verb ends in (e) , omit it before adding (ing).
EX:He is coming now.Correct.
*Use :
1- It is used to talk about an action that is happening now.It also mean that we are in the middle of an action.
EX:Look!They are playing.
2- It is used to express an action that is happening over a given period of time,not necessarily at the moment of speaking.
EX:I am reading a novel by Daniel Defoe.
I am reading it over a period of time not only at the moment of speaking.I may finish it in a week.
3-It is used to express an arranged future.
EX:I will travel to London next week.(I have booked a ticket)
*Negative:
We put (not)n't) to am/is/are.
I am not reading now.
He is not(isn't) sleeping .
They are not(aren't) running .
*Question:
-Yes or No question:
We invert the subject and the verb to be:Is he reading now. Yes ,he is. or No,he isn't
Are they running? Yes ,they are.Or no,the aren't
-Wh question:
EX:What are you doing at the moment?-I am cooking meat.
Note: These verbs aren't used in continuous tenses.
*Feeling:hate-like-love-prefer-want-wish
*Senses: appear-feel-hear-see-seem-smell-sound-taste
*Communication: deny-mean-surprise-satisfy-promise-agree-disagree
*Thinking:believe-imagine-know-realize-recognize-remember-understand
*possession:own-posses-belon-owe-have-involve-need-want-include
*There are some verbs which have another meaning so you can use them with continuous forms.
EX:I am thinking of going outside.
But If the speaker wants to express his openion ,he must use present simple not continuous.
EX:I think he is a good man.Not I am thinking.
*Some other verbs are used in continuous forms when the meaning changes.