Conditionals
·         The word ‘conditional’ refers to the sentence which has a condition mentioned in it.
·         To make a conditional sentence, we need a Main Clause and a Subordinate Clause.
·         For example:
If you step on snake, it will bite you.
Main Clause:                      It will bite you.
Subordinate Clause:        If you step on snake
(A clause is a sentence or is a part of a sentence which has a subject and a predicate)
Note: All the conditionals have the conjunction ‘If’. When we start a conditional with ‘if’, separate the two clauses by a comma.
Conditionals are of three types:
1.      The likely or probable conditional
2.      The unreal or hypothetical conditional
3.      The Impossible conditional
The Likely or Probable conditional:
Basic form of The Likely or Probable conditional
IF + present tense (subordinate clause)
Future tense (main clause)
If it doesn’t rain, we will play cricket.
IF + present tense
Imperative
If you go out, do not forget to bring the grocery.
IF + present tense
Present continuous
It the government doesn’t accept our conditions, we are extending our strike.
IF + Present continuous
Future tense
If you are looking for the Principal, you will find him in the auditorium.
IF + Present perfect
Future
If I have completed homework, I will watch television.
IF + present tense
May/might, must, should, can
If you love me, you must do the entire household.

We can also sometimes use 'should' in place of 'if' in more formal contexts:
Should the inflation continue to rise, the Reserve Bank of India will increase the interest rates.
The Unreal or Hypothetical conditional
Basic form of The Unreal or Hypothetical conditional
IF + Past tense
Would + bare infinitive
If I got the invitation, I would attend the wedding.
IF + Past tense
Might/Could + bare infinitive
·         If you worked hard, you would succeed (certain results)
·         If you worked hard, you might succeed (possible result)
·         If you worked hard, you could succeed (ability)
IF + Subject + were …. To make sentence more polite
If I were the Prime Minister, I would have done a lot for poor.

The Impossible conditional:
When a conditional is used to speculate about the past events and express regret or reproach, it is called as impossible conditional.
If you hadn't misled me, I would have attended the interview.
Basic form of The Impossible conditional
IF + past perfect
Would + have + past participle
If they had brought the man to the hospital immediately after the accident, his
life would have been saved.
IF + past perfect
Could/might
·         If we had found enough capital, we could have saved our business. (ability)
·         If we had found enough capital, we might have saved our business. (possibility)

Zero Conditional to express general truth
While expressing general truth in conditional sentence, the word IF is replaced by WHEN.
For example:
If (= when) water is heated to 100ºC (at STP) it boils.
OR
Water boils if (when) it is heated to 100ºC (at STP).
Conditionals without ‘If’
·         That/unless
We will go to Changu Lake on Saturday provided that/ unless the weather is fine.
·         Unless/as long as
Unless/ As long as the shop gives a good discount we will place our order with them.
·         Unless/ If
Unless/ If we look into his complaints the situation is going to get worse.
·         Provided that/unless
Provided that/ Unless you avoid the bandits, they will kill you.