Conditional sentences represent grammar structures answering the 'what if' question. Often there are three sentences used in the about principles that often begin with an "if." These two parts are sequentially placed and named a condition and a result. Knowing these patterns helps learners to present some outcomes, and certain situations, or express possible consequences.

For learners, it is important to note that conditions or conditional sentences can be further classified into four parts: Zero Conditional, First Conditional, Second Conditional and Third Conditional – each expresses different degrees of probability.

1. Zero Conditional

The Zero Conditional explains facts that are based on common sense. In these types of sentences, the condition and the result are both real and possible occurrences hence ensures that once a condition is satisfied, the outcome will happen.

They simply follow the positive present tense and are referred to as the Zero Conditional.

• If + present simple, present simple

The Zero Conditional may be applied in law, sociology, nature, biology when these disciplines explain the observable reality as it always exists while dealing with facts. Since both the condition and the result will always happen and time neither element possesses there is no hypothetical element in facts. It's the time element that remains most important that such an event will always happen and highlights the cause.

2. The First Conditional

The First Conditional is applied for the possible occurrences in the future. These types of conditional cases suppose a situation which is likely to happen and the operations that will follow this happening, are likely to happen also.

Structure:

• If + present simple, will + base verb

In the First Conditional sentences the situation is potential, but is not guaranteed. It describes events and actions that are most likely going to happen in future if the appropriate conditions are met. The result is a consequence of the condition happening and is in most circumstances realistic. This structure is generally used in when talking of the future; making predictions, sending warnings, issuing threats etc. It just 'bridges' a possible cause to the most likely effect.

3. The Second Conditional

The Second Conditional expresses a contrary to fact situation in the present or future. This conditional is used in situations where the speakers are talking about events that are not likely or are impossible in a given context, but are viewed as 'if' they were possible.

Structure:

• If + past simple, would + base verb

The Second Conditional concerns itself more with events that are only hypothetical and have no possibility of taking place right now. And even though the condition is already modeled in the past grammatical form, what is being addressed in the written sentence is either the present or the future. The chances of the condition being satisfied or even occurring are slim, thus the result is also imagined.

It is expected when one wants to talk about dreams and plans or situations that are hypothetical in nature and bear no relationship with reality. It should be acknowledged that though past tense is appropriate for the condition, the sentence does not concern past time – it concerns a situation that is unreal in the present or the future and never occurred.

4. Third Conditional

In the past situations that did occur, in accordance with the Third Conditional, there exists the ability to imagine a situation whereby other factors come into account and things could be different. This conditional describes events that are purely hypothetical. However in contrast to the Second Conditional, this conditional deals with situations which are not possible due to them being in the past.

Structure:

• 'If' + past perfect + would have + past participle

All of these phrases are termed The Third Conditional because they allow the speaker to express their regrets for things that did not happen in the past and how situations could have been different. The condition is an example of non-actualization of the objective, and the result is the achievement of the objective. It encompasses the essence of theory and examines events that took place in the past and points out how different things would have been if some conditions were different.

This structure is relevant for narrating events from the 3rd person perspective, where the narrator relates the story from the perspective of a character who is concerned with what did not occur in their life. Fiction, for instance, is full of instances when a character thinks about how their life could have been different.

Mixed Conditionals

In addition to these four main types, there is also the concept of Mixed Conditionals, this category consists of two or more parts with different conditional clauses since its name suggests they mix. It involves sentences that depict two or more aspects of complex time sequences. For example, they can give the results of previous events related to the present tense or narrate about previous situations in which the events have not started yet.

Structure:

• If clause: If + past perfect, main clause: would + base verb (in cases where present result pertains from a past cause)
• If clause: If + past simple, main clause: would have + past participle (in cases where presumptions are drawn to a present condition from past events)

Mixed conditionals are aptly named as they involve the combination of the cause in one time frame with the effect in another one while referencing a hypothetical situation. This variation always allows connecting the event that has happened to the real situation as it is today, or vice versa.

Key points to pay attention to

1. Verb Tenses : Each type of conditional sentence requires a specific combination of verb tenses that always goes with grammar, and are not left out. While Zero and First Conditionals make extensive use of present tense, the Second Conditional, using the past tense to refer to present or future hypotheticals, can sometimes be a bit tricky, and the Third Conditional contains the past perfect verb form.
2. Modal Verbs : As most of 'mother tongue' speakers will no doubt agree, the use of 'will' is by far the most common or frequent modal verb to use in conditionals, however, other modal verbs, such as 'might', 'could' or 'should' can also be used, but it all depends on the specific context.
3. Hypothetical and Real Conditions : Another pair of distinctions to be understood includes real conditions (zero and first conditional) from the unreal or hypothetical conditions (second and third conditional). The first two types treat a real, probable or general situation, while the last two types deal with situations which are either unlikely to happen or completely impossible.
4. Position of the "If" Clause : The "if" clause can be positioned at the beginning or at the end of a conditional statement whereas if it comes first, the condition and the result are separated by a comma. If the "if" clause comes second, this second clause does not require the use of a comma. The order in which the "if" clause is placed in a sentence does not change the meaning of the sentence but the order does change the stress or emphasis on the mote.

Asking and answering and other interrogative sentences which are dependent upon the use of conditional sentences gives learners the ability to formulate their thoughts in a more complex manner and enhances their ability to hypothesise regarding certain activities and their outcomes.