A present perfect verb always includes:
has (singular) or have (plural) + a past participle
Past participles usually end in -ed:
contributed, resigned, completed
but may be irregular:
fallen, grown, made, been, become
Examples
couples have contributed
average household size has fallen
A present perfect continuous verb includes:
has (singular) or have (plural) + been + an -ing verb
Examples
couples have been contributing
average household size has been falling
A present perfect passive verb includes:
has (singular) or have (plural) + been + a past participle
Examples
the report has been reviewed
prices have been increased
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