Modal verb — a verb (how can, could, should, should, wants or would be) that is usually used with another verb to express ideas such as possibility, necessity and permission — n. the right or ability to do something given by someone who has the power to decide whether it is allowed or allowed to help verbs or auxiliary verbs such as will, should, may, could, may, could, should, should, would be, would get used, should be used in conjunction with the main verbs to express nuances of tense and mood. Combining help verbs with main verbs creates what are called verbal sentences or strings of verbs. In the next sentence, «aura été» are auxiliary verbs or auxiliary verbs and «study» is the main verb; The whole string of verbs is underlined: in the absence of other modal aids, a form of C is questioned and negative constructions called passive: beware of May. If you apply with may, only I can be the subject. If you make a formal request to dance with someone, you would say, «Can I have this dance?» and not «Can you have this dance?» Can be followed by you does not express a request; it expresses a desire, as in «May you live long.» In English, modal verbs are called defective verbs because of their incomplete conjugation: they have a narrower range of functions than ordinary verbs. For example, most do not have an infinitive or gerund. Let`s see what this legal language really means. «We may collect information… » means that you authorize the Company to collect information about you.
In other words, you authorize the company to store your email address or computer address. A modal verb is a type of verb used to indicate modality, that is, probability, capacity, permission, demand, capacity, suggestions, order, commitment, or advice. Modal verbs always accompany the basic form (infinitive form) with another verb with semantic content.  In English, commonly used modal verbs are can, could, may, might, should, will, would and must. A third modal for polite requests is possible. For example, «Could I please have water?» Could be the past of can. However, if you ask permission, might make no sense in the past tense. The English could is the preterite form of can; should be the preterite of shall; Power is the preterite of the month of May; and Must was originally the preterite form of Mote. (This ignores the use of «may» as a vestige of subjunctive mood in English.) These verbs have acquired an independent present meaning.
The German verb want is sometimes taught as a vocabulary word and included in the list of modal verbs, but it is actually the past subjunctive form of like. This second table provides examples of each modal after its use, including an explanation. Note that, as in other Romance languages, in Italian there is no difference between an infinitive and a simple infinitive, so modal verbs are not the only group of verbs that accompany an infinitive (where in English there would be the form with «to» instead — see, for example, Ho preferito scappare («I preferred to escape»). Thus, while in English a modal verb can be easily recognized by the mere presence of a simple infinitive, there is no easy way to distinguish the four traditional Italian modal verbs from other verbs, except for the fact that the former are the only verbs that do not have a fixed auxiliary verb for the perfect. For this reason, some grammars also consider the verbs osare («to dare»), preferire («to refer to it»), desiderare («desire to»), solere («to use») as modal verbs, although they always use avere as an auxiliary verb for the perfect.  Modal verbs in Italian form a distinct class (verbi modali or verbi servili).  They can easily be recognized by the fact that they are the only group of verbs that does not have a fixed auxiliary verb for the formation of the perfect, but they can inherit it from the verb they accompany – Italian can have two different auxiliary verbs to form the perfect, avere («to have») and essere («to be»). There are a total of four modal verbs in Italian: potere («can»), volere («to want»), dovere («must»), sapere («to be capable»). Modal verbs in Italian are the only group of verbs allowed to follow this particular behavior. If they do not accompany other verbs, they all use avere («to have») as a verb to help the formation of the perfect. Germanic modal verbs are preterite-present verbs, which means that their present tense takes the form of a vocal preterite.