It would be incorrect to say "this headquarters"... it would have to be "those headquarters."
I've never heard it used in any singular form. You would have to say "this headquarter" which is never used.
Headquarters is both singular and plural.
The plural of headquarters remains headquarters.
Are is plural. "Is" is singular. For example, "There is a glove on the chair". That is singular. "There are gloves on the chair". That is plural.
Who may be singular or plural.
diagnosis is singular diagnoses is plural sis = singular ses = plural
Headquarters is both singular and plural.
Headquarters is a plural noun. It has no singular form
The plural of headquarters remains headquarters.
practitioner is singular (plural practitioners)sofa is singular (plural sofas)satellite is singular (plural satellites)clips is plural (singular clip)dentist is singular (plural dentists)dollars is plural (singular dollar)article is singular (plural articles)magazines is plural (singular magazine)laminator is singular (laminators is plural)radios is plural (singular radio)
singular and plural
Singular: book / Plural: books Singular: cat / Plural: cats Singular: child / Plural: children Singular: foot / Plural: feet
Are is plural. "Is" is singular. For example, "There is a glove on the chair". That is singular. "There are gloves on the chair". That is plural.
"Has" is singular, e.g. He has, she has. "Have" is plural, e.g. They have, we have. The exception is "I" - e.g. I have.
headquarters
The word team is singular; the plural form is teams.
Who may be singular or plural.
This is singular. These is the plural form.