Editing Defective verb (section)

=== Common defectives ===
<!--This article should mention that modal verbs = defective is an English thing!-->
The most commonly recognized{{citation needed|date=January 2024}} defective verbs in [[English language|English]] are auxiliary<!--SHOULDN'T IT BE MODAL? (modal verbs are a type of auxiliary verb, so it is correct the way it is)--> verbs—the class of [[preterite-present verb]]s—''can/could'', ''may/might'', ''shall/should'', ''must'', ''ought'', and ''will/would'' (''would'' being a later historical development). Though these verbs were not originally defective, in most varieties of English today, they occur only in a [[modal auxiliary]] sense. However, unlike normal auxiliary verbs, they are not regularly conjugated in the infinitive mood. Therefore, these defective auxiliaries do not accept each other as objects. Additionally, they do not regularly appear as participles.

For example, ''can'' lacks an infinitive, future tense, participle, imperative, and [[gerund]]. The missing parts of speech are instead supplied by using the appropriate forms of ''to be'' plus ''able to''. So, while ''I could write'' and ''I was able to write'' have the same meaning, ''I could'' has two meanings depending on use, which are ''I was able to'' or ''I would be able to''. One cannot say *''I will can'', which is instead expressed as ''I will be able to''. Similarly, ''must'' has no true past tense form, this instead being supplied by ''had'' (the past tense of have), and "to have to" in the infinitive, an example of composite conjugation. The past tense expressing the obligatory aspect of must is expressed as "had to", as in ''He had to go.'' "Must have", on the other hand, expresses probability or likelihood in modern English; for example, ''"If that's thunder, there must have been lightning."''

Some verbs are becoming more defective as time goes on; for example, although ''might'' is etymologically the past tense ([[preterite]]) of ''may'', it is no longer generally used as such (for example, ''*he might not go''{{efn|This article uses [[Asterisk#Ungrammaticality|asterisks]] to indicate ungrammatical examples.}} to mean "he was forbidden to go"). Similarly, ''should'' is no longer used as the past of ''shall'', but with a separate meaning indicating possibility or moral obligation. (However, the use of the preterite form ''should'' as a [[English subjunctive|subjunctive form]] continues, as in ''If I should go there tomorrow, ...'', which contrasts with the indicative form ''I shall go there tomorrow''.) The defective verb ''ought'' was etymologically the past tense of ''owe'' (''the affection he ought his children''), but it has since split off, leaving ''owe'' as a non-defective verb with its original sense and a regular past tense (''owed'').

Beyond the modal auxiliaries, ''beware'' is a fully defective verb in current Modern English: its only, unmarked form is regularly used (in simple aspect, active voice) in the infinitive (''I must beware of the dog''), imperative (''Beware of the dog, [Let the] buyer beware'') and subjunctive (''She insists that he beware of the dog''), but too much of the finite indicative mood is formally lacking (all simple past *''bewared'', one simple present *''bewares'', all aspects ''*am bewaring'', etc.). The word ''begone'' is similar: any usage other than as an imperative is highly marked. Another defective verb is the archaic ''quoth'', a past tense which is the only surviving form of the verb ''quethe'', "to say" (related to ''bequeath'').