Abstract
Modals are special verbs which behave very irregularly: - followed by the infinitive form without "to" - modal verbs do not take "-s" in the third person - there is no "do? or "did? in interrogative and negative forms - you use "not? to make modal verbs negative, even in simple present and simple past.
Can Ability:
Aptitude: "I can swim"
Authorization: "Can I go with you? "Yes of course, you can"
Willingness or possibility: "Can you pass me the paper?"
Could Ability in the past: "before his accident, he could run very fast"
Ability in conditional form: "could I phone you tonight?"
Would/ Will in conditional form: "Would you please stop sleeping?"
Steady habits in the past: "every Saturday, her husband would go to the pub"
