The furniture __________ very expensive.

The correct answer is is because 'furniture' is an uncountable noun in English grammar and must always be paired with a singular verb form.

• Step 1 (Definition): Uncountable (mass) nouns represent concepts, materials, or collections of items that cannot be counted individually without a counter phrase (like 'pieces of'). They strictly take singular verbs.


• Step 2 (Application): Since 'furniture' acts as a singular collective mass, it requires the singular present tense verb 'is' to maintain proper subject-verb agreement.


• Incorrect Options:
  
  
  
  • are is incorrect because it is a plural verb form, which cannot be paired with an uncountable subject.
  
  
  • were is incorrect because it is both plural and past tense, violating the singular agreement rule here.
  
  
  • have is incorrect because it is a plural helping or possessive verb that does not fit the adjectival predicate ('very expensive').