Sport in our life modal verb must ant have to a modal verb is a type of verb

Deduction[edit]

Main article: English modals of deduction
In English, modal verbs as must, have to, have got to, can't and couldn't are used to express deduction and contention. These modal verbs state how sure the speaker is about something.^[15][16][17]

• 
  You're shivering—you must be cold.
  
• 
  Someone must have taken the key: it is not here.
  
• 
  I didn't order ten books. This has to be a mistake.
  
• 
  These aren't mine—they've got to be yours.
  
• 
  It can't be a burglar. All the doors and windows are locked.
  

Double modals[edit]

In formal standard English usage, more than one modal verb is not used consecutively, as modals are followed by a base verb, which they themselves lack. They can be combined only with non-modal constructions that have a modal function, such as have to, which in spite of its function is not a modal verb. Thus, might have to is acceptable, but might must is not, even though must and have to can normally be used interchangeably. However the main auxiliary (which is usually the first modal verb in the sentence), does not have to be in the infinitive. To put double modals in past tense, only the first modal is changed as in I could ought to. Double modals are also referred to as multiple modals.^[18]
A greater variety of double modals appears in some regional dialects. In English, for example, phrases such as would dare to, may be able to or should have to are sometimes used in conversation and are grammatically correct.^[19] The double modal may sometimes be in the future tense, as in "I will ought to go," where will is the main verb and ought to is also an auxiliary but an infinitive. Another example is We must be able to work with must being the main auxiliary and be able to as the infinitive. Other examples include You may not dare to run or I would need to have help.
Some kinds of double modal phrases are not regarded as standard.^[19] "I might could do something," for instance, is an example of a double modal construction that can be found in varieties of Southern American and South Midland English.
To form questions the subject and the first verb are swapped if the verb requires no do-support such as Will you be able to write? If the main auxiliary requires do-support, the appropriate form of to do is added to the beginning, as in Did he use to need to fight?, as if normal modals are used the action verb needs to be in the infinitive form.
If modals are put in the perfect tense the past participle of the infinitive is used, as in He had been going to swim or You have not been able to skate, and to interrogate these the main verb and subject are swapped, as in Has she had to come?
Double modals also occur in the closely related Germanic language Scots.