Editing Interlingua (section)

== Grammar ==
{{Main|Interlingua grammar}}

Interlingua has been developed to omit any grammatical feature that is absent from any one primary control language. Thus, Interlingua has no [[agreement (linguistics)|noun–adjective agreement]] by gender, case, or number (cf. Spanish and Portuguese {{lang|es|gatas negras}} or Italian {{lang|it|gatte nere}}, 'black female cats'), because this is absent from English, and it has no progressive verb tenses (English ''I am reading''), because they are absent from French. Conversely, Interlingua [[grammatical number|distinguishes singular nouns from plural nouns]] because all the control languages do.{{sfn|Gode|Blair|1955}} With respect to the secondary control languages, Interlingua has articles, unlike Russian.

The definite article {{lang|ia|le}} is invariable, as in English ("the"). Nouns have no [[grammatical gender]].{{sfn|Gode|Blair|1955}}{{sfn|Wilgenhof|1995}} Plurals are formed by adding ''-s'', or ''-es'' after a final consonant.{{sfn|Gode|Blair|1955}} [[Personal pronouns]] take one form for the subject and one for the direct object and reflexive. In the third person, the reflexive is always ''se''.{{sfn|Gode|Blair|1955}}{{sfn|Wilgenhof|1995}} Most [[adverb]]s are derived regularly from [[adjective]]s by adding {{lang|ia|-mente}}, or {{lang|ia|-amente}} after a ''-c''. An adverb can be formed from any adjective in this way.{{sfn|Brauers|1975}}

Verbs take the same form for all persons ({{lang|ia|io vive}}, {{lang|ia|tu vive}}, {{lang|ia|illa vive}}, 'I live', 'you live', 'she lives'). The [[indicative]] ({{lang|ia|pare}}, 'appear', 'appears') is the same as the [[Imperative mood|imperative]] ({{lang|ia|pare!}} 'appear!'), and there is no [[subjunctive]].{{sfn|Gode|Blair|1955}} Three common verbs usually take short forms in the present tense: {{lang|ia|es}} for 'is', 'am', 'are;' {{lang|ia|ha}} for 'has', 'have;' and {{lang|ia|va}} for 'go', 'goes'.{{sfn|Wilgenhof|1995}} A few irregular verb forms are available, but rarely used.<ref>These are optional short forms for ''esser'', 'to be'. They are found in Wilgenhof, who stops short of calling them irregular verb forms. Two such forms appear in Gode and Blair, and one is labeled irregular; none are in Brauers.</ref>

There are four simple tenses (present, past, future, and conditional), three compound tenses (past, future, and conditional), and the passive voice. The compound structures employ an auxiliary plus the infinitive or the past participle (e.g., {{lang|ia|Ille ha arrivate}}, 'He has arrived').{{sfn|Gode|Blair|1955}} Simple and compound tenses can be combined in various ways to express more complex tenses (e.g., {{lang|ia|Nos haberea morite}}, 'We would have died').<ref>See for example {{harvtxt|Gode||Blair|1955}}, {{cite web|url=https://members.optus.net/~ado_hall/interlingua/gi/parts_of_speech/verb.html#115 |title=§115, "Table of Conjugation"|archive-url=https://web.archive.org/web/20070221093610/http://members.optus.net/~ado_hall/interlingua/gi/parts_of_speech/verb.html#115 |archive-date=2007-02-21|url-status=dead}}, pp. 38–40.</ref>

Word order is [[subject–verb–object]], except that a direct object pronoun or reflexive pronoun comes before the verb ({{lang|ia|io les vide}}, 'I see them').{{sfn|Gode|Blair|1955}}{{sfn|Wilgenhof|1995}} Adjectives may precede or follow the nouns they modify, but they most often follow it.{{sfn|Gode|Blair|1955}} The position of adverbs is flexible, though constrained by common sense.{{sfn|Wilgenhof|1995}}

The grammar of Interlingua has been described as similar to that of the Romance languages, but simplified, primarily under the influence of English.{{sfn|Gode|Blair|1955}} A 1991 paper argued that Interlingua's grammar was similar to the simple grammars of Japanese and particularly Chinese.{{sfn|Yeager|1991b}}

F. P. Gopsill has written that Interlingua has no irregularities, although Gode's ''Interlingua Grammar'' suggests that Interlingua has a small number of irregularities.{{sfn|Gode|Blair|1955}}{{sfn|Gopsill|1994}}