Modal Forms
Modal verbs can be used in a variety of different forms. Study the examples below.
Modal Simple
I could swim at the beach.
Passive Modal Simple
The room should be cleaned once a day.
Modal Continuous
I could be swimming at the beach right now.
Passive Modal Continuous
The room should be being cleaned now.
Modal Perfect
I could have swum at the beach yesterday.
Passive Modal Perfect
The room should have been cleaned yesterday.
Modal Perfect Continuous
I could have been swimming at the beach instead of working in the office.
Passive Modal Perfect Continuous
The room should have been being cleaned but nobody was there. (Rare form)