Tenses tenses denote the time of action. They show when the work is done. They are: (1) Present Tense (2) Past Tense (3) Future Tense They are further divided into: (1) Simple Present

Did + Subject + not + V1 + Object + (?) 
Did she not write a letter? 
Past Continuous Tense 
Used to denote an action going on at some time in the past. 
e.g. I was driving a car. 
Rule: was/were + ing 
1.
Assertive Sentences –
Subject + was/were +V1+ ing + Object + (.)
She was writing a letter. 
2.
Negative Sentences- 
Subject + was/were + not + ing + Object + (.) 
She was not writing a letter. 
3.
Interrogative Sentences- 
Was/were + Subject + ing+ Object + (?) 
Was she writing a letter? 
4.
Interrogative Negative Sentences- 
Was/were + Subject + not + ing+ Object + (?) 
Was she not writing a letter? 
Past Perfect Tense 
Used to describe an action completed before a certain moment in the past, usually a 
long time ago. If two actions happened in the past, past perfect is used to show the 
action that took place earlier. 
e.g. The patient had died before the doctor came. 
1.
Assertive Sentences –
Subject + had + V3 + Object + (.)
She had written a letter. 
2.
Negative Sentences- 
Subject + had + not + Object + (.) 
She had not written a letter. 

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3.
Interrogative Sentences- 
Had + Subject + V3 + Object + (?) 
Had she written a letter? 
4.
Interrogative Negative Sentences- 
Had + Subject + not + V3 + Object + (?) 
Had she not written a letter? 
Past Perfect Continuous Tense 
Used to denote an action that began before a certain point in the past and continued 
up to some time in past. 
e.g. I had been learning English in this school for 20 days. 
1.
Assertive Sentences –
Subject + had been +V1 + ing + Object + (.)
She had been writing a letter. 
2.
Negative Sentences-