1. A Modal verb is a type of verb that is used to indicate modality that is: likelihood, ability, permission, request, capacity, suggestions, order, obligation, or advice. Modal verbs always accompany the base form of another verb having semantic content.
1.1. examples
1.1.1. CAN
1.1.1.1. Positive
1.1.1.1.1. Can is used to express ability or to say that something is possible. Can is the same for all subjects. We don't add an 'S' in the third person (like other verbs)
1.1.1.2. Negative
1.1.1.2.1. To form the negative we add "not" after can to form one word: cannot. We can also contract the negative to form can't. (can't = cannot)
1.1.1.3. Impersonal Can
1.1.1.3.1. Sometimes You can and Can you…? are impersonal and refer to people in general. It doesn't necessarily refer to you but people in general.
1.1.1.4. Questions
1.1.1.4.1. To from the question we change the position of the subject and the auxiliary verb. The main verb is still in the infinitive without to.
1.1.2. SHOULD
1.1.2.1. What is ideal or desired
1.1.2.1.1. We use should most commonly to talk about what is the ideal or best thing to do in a situation:
1.1.2.1.2. We use should have + -ed form to talk about things that were ideal in the past but which didn’t happen. It can express regret:
1.1.2.2. Advice and suggestions
1.1.2.2.1. We often use should to give advice and make suggestions
1.1.2.3. What is likely to happen
1.1.2.3.1. We also use should to talk about what is likely to happen:
1.1.2.4. Conditional sentences
1.1.2.4.1. Warning
1.1.3. HAVE TO
1.1.3.1. is a construction (structure). It is not a modal verb. We use auxiliary verbs do and does to form questions and negatives. With have got to negatives and questions are formed differently.
1.1.3.1.1. examples