Assertion: auxiliary verb's form | /r/HasProperty | rare
Facets:
value: quite
type: DEGREE
Source sentences:
text: The passive forms of certain of the combinations involving the progressive aspect are quite rare; these include the present perfect progressive (it has been being written), past perfect progressive (it had been being written), future progressive (it will be being written), future perfect progressive (it will have been being written), conditional progressive (it would be being written) and conditional perfect progressive (it would have been being written).