Defective Verbs + Perfect Infinitive
When defective verbs are followed by have + past participle, they indicate a past action. That action was not fulfilled or other way round.
Need – Dare
Defective verbs - Need / ni:d / and Dare. The ver need is used as a defective verb and as a regular verb. The defective verb need has only the present tense, takes no -s in the 3rd person singular.
Must – Ought – Should
Must express a necessity, a command or a probability. Ought to and should express moral obligation or a probability. Verb ought is more emphatic than verb should. Verb should is often used when subject is asking or giving advice. Also should often indicates a recommendation rather than obligation.
Can & May
Can and May, are two verbs that have only the past tense and the present tense. Verbs may and can express - ability, capability.
Defective Verbs | Defective Verbs in English language are - can, may, must, ought, should.Common characteristics of these verbs