You might be aware about the fact that “when” conjunction is mainly used to introduce adverb clause of time. In order to describes an action happening at a point of time, when conjunction of time is preferred. In short, the implied meaning of when is–at that time, and is used for sureness. Whereas, “if” conjunction of condition is used for possibility. Let’s know the basic difference between when and if conjunctions..
•When > point of time, at that time, close sequence between two actions.
•When is used for sureness of situation.
•When + dependent clause + comma + main clause.
•Main clause + when + dependent clause.
But, sometimes, “when” conjunction is also used to express conditions along time as well…
Future auxiliary verbs aren’t used in the when clause. Instead, present auxiliary verbs are preferred for future sense.
Useful examples of adverb clause of time -“when”
•It was the time of tension and insecurity when the world divided into two poles.(when ? At that time– Cold War)
•He used to visit national parks when he was in the Kenya.(occasion of Kenya visit)
•When we visited tribal regions, we worked for tribal cause.
•When is used to express actions in a sequence with minimum gap.
•When the bus arrived, the passengers had already left the bus stop.
•We had already covered the ground when it started raining.
•When they declared ceasefire, thousands of people had been killed.
•For the future tense, simple present is used, and “Will” is not used in the when clause.
•I will assist you when I finish job.
•Temperature will come down when the carbon emissions decrease.
•The situation will become serious when the rain delays.
To understand the difference between when and if conjunctions, we need to take a close look at the meaning and use of “if” conjunction of condition..
Conjunction of condition – “If”
Though the conditional sentences are used to express the hypothetical scenarios, “if” conjunction of condition is used to describe possibility in conditions.
Rules of use of “If”
•In the basic level of conditional sentences, general truth or possibility is described with simple present in both clauses.
•In the present, “If” is used to begin a dependent clause, but in the second main clause will is generally used.
•In the past sense of conditional sentences, would is preferred in place of will.
•Comma is introduced to separate two parts of sentence only when the If clause is used to begin the sentence.
•If you sow seed, it returns as fruit.
• If clause + main clause. (simple present + future)
•If I learn english grammar, I will speak fluently.
•If I receive my first salary, I will give a party for you.
•If he arrives on time, I will escort him carefully.
•If he invites, I may think positively.
In these examples, second main clause is the possible outcome of the earlier condition. By studying this, you may well understand the basic difference between when and if conjunctions….