The original link: https://www.thefreedictionary.com/Subjunctive-Mood.htm#Using%20the%20Subjunctive%20Mood

What is the subjunctive mood?

The subjunctive mood refers to verbs that are used to describe hypothetical or non-real actions, events, or situations. This is in comparison to the indicative mood, which is used to express factual, non-hypothetical information.

We most commonly use the subjunctive mood to express desires or wishes; to express commands, suggestions, requests, or statements of necessity; or to describe hypothetical outcomes that depend on certain conditions.

Using the Subjunctive Mood

Verbs do not have different forms to express the subjunctive mood in English. Instead, they are conjugated a certain way depending on the meaning we wish to achieve.

Expressing Wishes

When we express a wish for something to be true, we conjugate the verb one degree into the past to create the subjunctive mood. For example:

Indicative mood: 「It』s Monday. I have to go to work.」
Subjunctive mood: 「I wish it weren』t* Monday. I wish I didn』t have to go to work.」

(*Conventionally, the verb be always conjugates to were in the subjunctive mood, regardless of whether it refers to a singular or plural noun. However, it has become common in modern English to conjugate be to was when it has a singular subject.)

Expressing Commands, Suggestions, Requests, and Statements of Necessity

When we express actions that we demand, suggest, or request that someone else take, or describe something that must be the case, we use the base form of the verb—that is, the infinitive form without the word to.

For example:

「He demanded that they leave the room at once.」 (command)
「I recommend that she study harder next time.」 (suggestion)
「I ask that the audience be completely silent during the demonstration.」 (request)
「It』s necessary that we be vigilant to avoid another disaster.」 (statement of necessity)

The biggest difference between the subjunctive and indicative mood in this case is that the verb does not change according to who is taking the action. For instance, it is she study, the audience be, and we be in the subjunctive, while it would be she studies, the audience is, and we are in the indicative mood.

Note that when we issue direct demands using imperative sentences (as in, 「Do your homework!」 or 「Please close the window.」), we are no longer using the subjunctive mood—instead, we are using what』s known as the imperative mood.

Conditional Sentences

Conditional sentences are used to describe hypothetical scenarios that require a certain condition or conditions to be met. They use what』s known as the conditional mood and are generally constructed using if to identify the conditions that must be met.

There are four 「degrees」 of conditionals, all of which vary in structure and meaning. We』ll give a brief synopsis of the different conditionals below; see the section on Conditional Sentences to learn more about how they are formed and used.

Zero Conditional

The zero conditional is used to talk about something that is generally true. For instance:

「If you throw a ball in the air, it comes back down.」 (Always true: A ball will come back down every time you throw it in the air.)

First Conditional

The first conditional is very similar in structure to the zero conditional, except that we now use the future simple tense (will + bare infinitive) to describe a probable or intended result of the condition. For example:

「If I see him, I will tell him.」
「If I win the lottery, I will buy a new house.」

Second Conditional

We use the second conditional to speak about a hypothetical situation or outcome resulting from the condition. Unlike the first conditional, we generally use the second conditional to talk about things that cannot or are less likely to happen.

To create the second conditional, we use the past simple tense after the if clause, followed by would, could or might + the bare infinitive for the result of the condition. For example:

「If you had a phone, you could call me every day.」
「If I were older, I might stay up all night long.」

Third Conditional

Third conditionals are used to establish a hypothetical situation in the past, followed by a hypothetical outcome that did not really happen—typically, the outcome is the opposite of what actually happened.

To form the third conditional, we use the past perfect tense for the if conditional clause, and would/could/should/might have + the past participle of the verb for the hypothetical outcome.

「If I had been more prepared, I would have passed that test.」
「If I hadn』t overslept, I wouldn』t have been late for work.」