Perfectives with Modals: Expressing Past Possibility and Obligation

Perfectives are formed by using "have" with the past participle form of verbs. They are commonly used with perfect tenses and unreal conditionals. In addition, perfectives can be used with modals to indicate past possibility and obligation. Modals + Perfectives Modals can be combined with perfectives to express past possibility and obligation. Basic Structure: Subject + modal + have + verb in past participle + ... Note: A modal is always followed by "have" because a modal requires the base form of the verb after it. So, a modal cannot be followed by "has" or "had". Could/May/Might + Perfective To indicate a possibility that occurred in the past, you can use these modals with perfectives. Structure: Subject + could/may/might + have + verb in past participle + ... Example: It might have rained yesterday, but I am not sure. Example: You could have stayed here last night. Example: Alex may have reached there by yesterday. Example: I saw a mobile phone on my sofa; Ne…