Modal verbs

dal verbs are:

The modal verbs are:

CAN / COULD / MAY / MIGHT / MUST / SHALL / SHOULD / OUGHT TO / WILL / WOULD 

 A table with the different modal verbs

Modal verbs are special verbs

1. Modal verbs do not take "-s" in the third person,  e.g., He can  speak Chinese.

2. You use "not" to make modal verbs negative, even in Simple Present and Simple Past, e.g., He should not be late..

3. Many modal verbs cannot be used in the past tenses or the future tenses.

    Source: http://www.englishpage.com/modals/modalintro.html

    More Explanations in Portuguese

Try these exercises

http://www.englishpage.com/modals/modalintro.html

http://www.perfect-english-grammar.com/modal-verbs.html