Present Tense, Simple Present Tense, Kinds of Present Tense

Present Tense (Simple Present Tense)
There are Four Kinds of Present Tense.
PRESENT INDEFINITE (SIMPLE PRESENT TENSE)
Syntax: Sub+V1
I write a letter.
She makes a doll.
Note:Use s/es with the 1st form of the verb if the Subject is He/She/It or singular Noun (boy, player, teacher, Khalid, Zara etc).
Negative: Sub+do/does+not+V1
We do not write poems.
Qasim does not play football.
Interrogative: Do/Does+sub+V1
Do you go to market?
Does she go for a walk?
Int. & Neg: Do/Does+sub+not+V1
Do you not go to bazar?
Does she take tea?
PRESENT CONTINUOUS
Syntax: Sub+is/am/are+V1+ing
Mohan is reading.
Negative: Sub+is/am/are+not +V1+ing
They are not playing cricket.
Interrogative: Is/Am/Are+sub+V1+ing
Is he going?
Int. & Neg: Is/Am/Are+sub+not+V1+ing
Are you not playing cricket?
PRESENT PERFECT
Syntax: Sub+has/have+V3
She has made tea.
Negative: Sub+has/have+not+V3
They have not taken medicine.
He has not come since Monday.
Int: Has/Have+sub+V3
Have they slept?
Int. & Neg: Has/Have+sub+not+V3
Have you not done your home-work?
PRESENT PERFECT CONTINUOUS
Syntax: Sub+has/have+been+V1+ing+since/for
I have been reading since 5 O'clock.
Negative: Sub+has/have+not+been+V1+ ing+ Since/for
Khalid has not been playing since evening.
Int: Has/Have+sub+been+V1+ing+since/for
Have you been working for ten minutes?
Int. & Neg: Has/Have+sub+not+been+VI+ing+since/for
Has she not been praying for five minutes?
Use of Since: (For point of time) 10am, 6 O'clock, morning, 21st May, January,2002, when, then, yesterday, last year/month etc.
Use of For: (For period of time) 2 days, 4 minutes, 2 hours, 7 months, 3 years, many days/months etc.
Reference:
http://www.googleurdu.com/
http://www.youtube.com/watch?v=yWccPqg1DbI