Type of Tenses: Present tense, Past tense, Future tense

Simple Present Tense 

Simple Present Tense sentences include happening of work in present time.
Subject + 1 st form of Verb
1. Subject (Singular form /third person) + 1st Form of Verb + s/es
Noun Subject is also a third person.
2. Subject(Plural ) + 1st Form of Verb
3. For I and You , we will not use 's' and 'es' with Verb.
Example :I study on daily basis.

Present continuous tense

Expresses an action continued at present time.
1. Subject (Singular /third person/He,She,It) + is + (1st Form of Verb + ing) + Object
2. Subject (Plural /You,We,They) + are + (1st Form of Verb + ing) + Object
3. I + am + (1st Form of Verb + ing)

Example:I am reading a novel.
Ram is going office.
We are getting late.
Present perfect tense

An action which happened or completed in the present time
1. Subject (Singular /third person/He,She,It) + has + 3rd Form of Verb + Object
2. Subject (Plural /I,You,We,They) + have + 1st Form of Verb + Object

Example:Divya has gone to school.
He has filled a case.
Past Tense :-
Simple Past Tense

1. Subject (Singular/third person/Plural ) + 2nd Form of Verb
2. Different number of subject can not change verb.

Example:I worked on the project last night.
Past continuous tense

1. Subject (Singular /third person/He,She,It) + was + (1st Form of Verb + ing) + Object
2. Subject (Plural /You,We,They) + were + (1st Form of Verb + ing) + Object

Example :
I was reading harry potter last night
Past perfect tense

An action which happened or completed in the past time or usually the two actions which happened or completed one by one in the past time.
1. Subject (Singular /third person/Plural ) + had + 3rd Form of Verb + Object

Example:Ramya went to school after she had completed her homework.
I had already heard this news.
Future Tense
Simple future tense

1. Subject (Singular/third person/Plural) + will + 1st Form of Verb
2. I or We + shall + 1st Form of Verb

Example:
We shall go to school tomorrow.
You will read a book.
Future continuous tense

1. I,We + Shall be + (1st Form of Verb + ing) + Object
2. Subject(Other than I,We) + will be + (1st Form of Verb + ing) + Object

Example:We shall be coming to your house.
We will be playing football in evening.
Future perfect tense

1. Subject + will have/shall have + 3rd Form of Verb + Object
2. Wherever you'll see the use of the two sentences in this tense, the action which would be completed first would be in 'Future Perfect Tense' and the action completed after would be in 'Present Simple Tense'.

Example:They will have played the match before the sun sets.
I shall have read my book before you come.
Rule 1. In Present Indefinite sentences the number and the person of the subject play very important role. If the subject is Singular number third person, affix ‘s’ or ‘es’ to the verb. If the verb ends in any of the following : ss, o , x, z, sh,ch , add, ‘es’ instead of ‘s’ with the verb.
Eg: Pass-passes, miss-misses, do – does, mix – mixes, fix – fixes etc.
Rule 2.When the main verb is in Future Tense, use Present Simple in clauses with if, till, as soon as, when, unless, before, until, even if, in case and as. 

Eg:

    We shall wait till she arrives. 
    I shall not go there even if it rains. 

Rule 3.Present Simple Tense must be used instead of Present Continuous Tense with verbs of perception (feel, hear, smell etc.), verbs of cognition (believe, know, think etc.), verbs of emotion (hope, love, hate etc.) which cannot be used normally in continuous form.
Eg:

    Incorrect – We are seeing with our eyes. Correct – We see with our eyes. 
    Incorrect – The water is feeling cold. Correct – The water feels cold. 

But these words can be used in progressive form in the following cases.

    The Session Judge is hearing our case. 
    We are thinking of going to London next year. 
    I am seeing my lawyer today. 
    I am having some difficulties with this puzzle. 

Rule 4.One must not use adverbs of past time like yesterday, last year, last month, ago, short while ago etc. with Present Perfect Tense. 

Eg:

    Incorrect – He has completed his book yesterday. Correct – He completed his book yesterday. 
    Incorrect – We have met 3 days ago. Correct – We met 3 days ago. 

Rule 5.If two or more actions took place in sequence, we use Simple Past to denote the actions. (Otherwise Past Perfect is used to denote the earlier action). This is usually used with conjunction Before. 

Eg:

    He switched on the light before he opened the door. 
    The train started just before I reached the station. 
    When Rahul reached home, Tina had had her lunch. 

Rule 6.The use of Simple Past Tense with , ‘wish’ and ‘If only’ shows unreal Past and present state of things. 

Eg:

    I wish I were a millionaire! (I am not a millionaire) 
    I wish I were a queen! (I am not a queen) 
    If I only knew her! (I don’t know her.) 

Rule 7.In the following structure the use of Simple Past denotes unreal past and present time situation. 

Eg:

    It is time we went home. (It is time for us to go home.) 
    It is time you finished. (It is time for you to finish.) 

Rule 8.Use of Past Continuous with ‘When’ and ‘While’
When is usually used when one action was completed and another action was going on. 

When gives the meaning ‘at the time that’. 

Eg:

    When he arrived, his wife was washing her clothes. 
    When she went to Banaras, she bought a sari. 

While is used to denote a period. 

Eg:

    While I was teaching, I put through my best. 
    While I was in Opera, I could enjoy very much. 

Rule 9.Past Perfect is used when we look back on earlier action from a certain point in the past. 

Eg:

    She had completed her work, before I reached there. 
    I had started teaching before Manu came to my class. 

Rule 10.The Past Perfect is also used for an action which began before the time of speaking in the Past and which stopped sometime before the time of speaking.

 Eg:

    He had served in a bank for twenty years; then he retired and established his business. His children were now well settled. 

Rule 11.Past Perfect Continuous is used when the action began before the time of speaking in the past, and continued up to that time. 

Eg:

    It is now eight and she was tired because she had been cleaning the house since dawn. 
    This city has been prosperous since a very long time. 

Rule 12.When two actions are to be taken place on some future time, we use Future Perfect for the action completed first and Present Simple for the action to be completed afterwards.
Eg:

    The student will have left the class before the teacher comes. 
    The Principal will have started before I reach there. 

Rule 13.Future Perfect is also used for such incidents/actions about which we presume that another person had the knowledge of that incident or the action is already completed. 

Eg:

    You will have heard about Mother Teresa. 
    He will have read the newspaper so far.