Subjunctive mood (grammatical verb form)

The grammatical subjunctive mood of a verb indicates a hypothetical or necessity.

The subjunctive mood marks several grammatical functions, usually working with "that" and "be"

Types of subjunctives

(In the below examples, the subjunctive mood verbs are in bold)

express urgency, a request or a recommendation

examples

I suggest [that] you get moving
- as opposed to "I suggest punctuality"
She asked that I finish by noon
- as opposed to "She asked me to finish by noon," which is not subjunctive
The program requires that students complete their exams
- as opposed to "The program requires completion of exams"

express advice or recommendation, often formal or evaluative

examples:

usually "if statement" that express a hypothetical or desire for an outcome that does not already exist:

Structure	Subjunctive Sentence	Same idea expresed without the subjunctive	Note
If...were	If I were taller, I'd play basketball.	If I was taller, I could play basketball.	the subjunctive mood employs bare verbs (without subject-verb matching; whereas the "indicative" mood verbs match to the subject the indiciative mood is also less formal than the subjunctive mood
I wish...were	I wish she were here.	I wish she was here.
As though / as if	He talks as though he were the boss.	He talks like he is the boss.
Suppose / Imagine that...	Suppose he were late—what then?	Imagine he was late—what would we do?

Category	Trigger Expression	Example Sentence	Notes
Mandative Verbs	suggest	I suggest that she arrive early.	Typically followed by a "that"-clause with bare verb form.
	recommend	They recommended that he study abroad.
	insist	She insisted that he be present.
	demand	He demanded that the report be revised.
	propose	We proposed that the meeting start later.
	ask	They asked that she submit it by noon.
	require	The school requires that students be punctual.
Adjectival Expressions	It is essential that...	It is essential that he arrive on time.	Often formal; signals necessity or importance.
	It is important that...	It is important that she be heard.
	It is necessary that...	It is necessary that they speak freely.
	It is appropriate that...	It is appropriate that he take charge.
	It is advisable that...	It is advisable that she consult a specialist.
Hypotheticals & Wishes	If...were	If I were taller, I'd play basketball.	Classic counterfactual subjunctive form.
	I wish...were	I wish she were here.	"Were" used instead of "was" in all persons.
	As though / as if	He talks as though he were the boss.
	Suppose / Imagine that...	Suppose he were late—what then?
Fixed Expressions	God bless you	God bless* you.*	Idiomatic (just that way) subjunctive.
	Heaven forbid	Heaven forbid* we be wrong.*
	Be that as it may	Be that as it may, we continued.
	Come what may	Come what may, she won't leave.
	Long live...	Long live* the king!*	"live" is subjunctive, even in archaic or ceremonial speech.

Notes:

"subjunctive forms" in English rarely employ "morphological changes" (tense, conjugation, or other stem changes);

the "bare" verb (i.e. "arrive" instead of "arrives") and the verb "be" in all subject perspectives (person, i.e., "I", "you", "it", "they") are key indicators of the subjunctive mood.