Modal verbs are special verbs that behave differently than regular verbs. Some key differences are that modal verbs don't take -s in the third person, use "not" for negatives rather than past/present forms, and many can't be used in past/future tenses. Common modal verbs include can, could, have to, may, might, must, ought to, shall, should, will, and would. Each modal verb has specific meanings and uses around ability, permission, possibility, necessity, recommendations, and future/conditional forms.

1. Modal ContinuousModal Perfect ContinuousModal Verb Modal verbs are special verbs which behave very differently from normal verbs.Modal verbs can be used in a variety of different formsI could swim at thebeach.Modal SimpleI could be swimming atthe beach right now.I could have swum at the beach yesterday.Modal PerfectI could have been swimming at the beach instead of working in the office.The room should be cleaned once a day.Passive Modal SimpleThe room should be being cleaned now.Passive Modal ContinuousThe room should havebeen cleaned yesterdayPassive Modal PerfectThe room should have been being cleaned but nobody was therePassive Modal Perfect Continuous

2. Modal verbs are special verbs which behave very differently from normal verbs. Here are some important differences: Modal verbs do not take "-s" in the third person. Examples:He can speak Chinese. She should be here by 9:00.You use "not" to make modal verbs negative, even in Simple Present and Simple Past. Examples:He should not be late. They might not come to the party.Many modal verbs cannot be used in the past tenses or the future tenses. Examples:He will can go with us. Not CorrectShe musted study very hard. Not CorrectCan

3. Could

4. May

5. Might