hoeveel

how much, how many

onderzoek

• Noun

  1. research, experiment, study, trial, test, survey
  2. investigation, inquiry, examination, survey

• Verb

er

1. there (unspecific to distance)
2. it; him, her, them.

gedaan

past participle of doen

de

• Article

  the (definite article, masculine and feminine singular, plural)

• Prep

luchtkwaliteit

air quality

is

• Verb

  third-person singular present indicative of zijn; is, equals

• Adv

onbekend

1. unknown
2. anonymous