Overview of Conditional sentences

In this module we will cover the following topics:

• What are Conditional sentences?

• Types of Conditional sentences

What is a Conditional sentence ?

Conditional sentence - When two actions take place one after the other, the second depending on the first.

Conditional sentences have two parts:

• Conditional clause (or If clause).
• Main clause

You will get selected provided you practice regularly. OR
You will get selected if you practice regularly.

Main clause - You will get selected
Conditional clause – if/provided you practice regularly

You will generally find these words in conditional sentences:

• If
• Provided
• As soon as
• No sooner
• Unless
• Until
• When
• As soon as
• Before/After
• In case
• Lest

Types of Conditional sentences

There are basically three types of Conditional sentences that you will find, wherein:

• conditional clause is in present tense.

• conditional clause is in past tense.

• conditional clause is in past perfect tense.

Conditional clause in present tense

Case 1

When two actions take place one after the other in future, and if the second action depends on the first action, then:

• the first action is described in conditional clause, which is in simple present tense and
• the second action is described in main clause, which is in simple future tense.

Pattern: Conditional word (e.g. if) + Simple Present, Simple Future

If I will come to London, I will attend your party. (incorrect)
If I come to London, I will attend your party. (correct; If I come to London – conditional clause describing the first action in simple present tense)

So, we know that main clause is in simple future tense. But we do not always use ‘will’ in it. Sometimes we use other modal verbs too.

• We use ‘may/might’ if a probability is expressed.
  If the fog stays, our flight may get late. (it’s probable)  
• We use ‘may’ if the sentence is regarding permission.
  If you have completed your homework, you may go out to play. (permission granted)  
• We use ‘should/must’ if the sentence is related to a suggestion.
  If you want to be among the toppers, you should study daily. (suggestion given)  
• We use ‘could/may’ if sentence is related to requests with respect.
  If you go to the Post office, would you post this letter for me? (a request)

Case 2

Sometimes the whole sentence can be in simple present tense. That is:

• the first action is described in conditional clause, which is in simple present tense and
• the second action is described in main clause, which is in simple present tense .

Pattern: Conditional word (e.g. if) + Simple Present, Simple Present

If it rains, the school remains closed.

Case 3

Sometimes the conditional clause can be in present continuous tense (rather than in simple present tense).

If you are not studying, you should help your mother.

Case 4

Sometimes the conditional clause can be in present perfect tense (rather than in simple present tense).

If you have finished your homework, you may go out and play.

Conditional clause in past tense

Sometimes the conditional clause can be in simple past tense. Conditional of this type is used when we talk about something which is purely imaginary.

Pattern: If + Simple Past, Subject + would + $V_1$

If I had the cure, I would lend it to you Mr. Green. (it means that subject does not have the cure, i.e. subject is describing an imaginary situation.)

Conditional clause in past perfect tense

Concept 1

Sometimes the conditional clause can be in past perfect tense. Conditional of this type is used when something did not happen because a certain condition was not fulfilled.

Pattern: If + Past Perfect, Subject + would + have + $V_3$

If I had invented the vaccine, I would have given it to you Mr. Green. (it means that subject does not have the vaccine, i.e. subject is describing something that did not happen.)

Concept 2

In such sentences we can also replace ‘if’ with ‘had’ (without changing the meaning of the sentence).

Pattern: Had + Subject + $V_3$ + Object, Subject + would + have + $V_3$

Had I invented the vaccine, I would have given it to you Mr. Green.

Other words and phrases used to introduce conditional clauses

Let us see other words and phrases that we can use to introduce conditional clauses (i.e. apart from if)

Unless

When we use ‘unless’ in conditional clause, it essentially means ‘if … not’. So, we do not use “not” with unless. (we do not use ‘not’ with until either).

Unless + affirmative = If + negative

You can’t sit here unless you have a ticket. (correct) OR
You can’t sit here if you do not have a ticket. (correct)

Unless Vs. If not

In most real conditional sentences, we can use either ‘unless’ or ‘if…not’ with a similar meaning.

However, there are instances wherein we prefer one over the other.

We use ‘if…not’ but not ‘unless’, in the following cases:

• in most unreal conditional sentences:
  
  Unless he had chosen the path of crime, he would have been a successful lawyer. (incorrect; meaningless)
  If he had not chosen the path of crime, he would have been a successful lawyer. (correct)

• when we talk about emotions:
  
  I will be surprised unless you win. (incorrect; meaningless)
  I will be surprised if you do not win. (correct)

Whether

We use ‘if’ or ‘whether’ in following cases:

• to talk about two possibilities, or
• to say that people are not sure about something:

We could not decide whether/if it was worth investing in Sun Pharma’s share.

I doubt whether/if you want to join our organization.

Concept 1

‘whether’ can usually be followed directly by ‘or not’. But ‘if’ is not directly followed by ‘or not’.

Compare:

I do not know if or not Messi is playing. (incorrect)
I do not know if Messi is playing or not. (correct)

I do not know whether or not Messi is playing. (correct)
I do not know whether Messi is playing or not. (correct)

Concept 2

We prefer ‘whether’ rather than ‘if’ in following cases:

• after the verbs advise, consider, discuss.
  
  You should consider carefully whether you want to become an engineer.

• before to-infinitives and after prepositions.
  
  I could not decide whether to buy an air conditioner or cooler. (to buy - infinitive)
  We argued about whether she should become a banker or an inspector. (about - preposition)

Conditional sentences and Verbs

If the first verb in a conditional if-clause is one of the following, then we can leave out ‘if’ and put that verb at the start of the clause:

• should
• were
• had

Should

If any of this should cause you any discomfort, just let me know. (correct)
Should any of this cause you any discomfort, just let me know. (correct; verb ‘should’ put at the start)

Were

It would be a great confidence booster, if he were to qualify the prelims. (correct)
It would be a great confidence booster, were he to qualify the prelims. (correct; verb ‘were’ put at the start)

If it wasn’t/weren’t for Alfred, the meeting wouldn’t be going ahead. (correct)
Were it not for Alfred, the meeting wouldn’t be going ahead. (correct)

Had

If they had not called the ambulance quickly, she would have died. (correct)
Had they not called the ambulance quickly, she would have died. (correct; verb ‘had’ put at the start)

If it had not been for my parents, I would never have finished my rehab. (correct)
Had it not been for my parents, I would never have finished my rehab. (correct)

Extra Books and Tools

If you prefer to learn via books, or want some good English Grammar books for reference purposes, you may read this article which enlists some of the books recommended by us.