Question

select the three adjectives. don’t select any articles (a, an, or the). charles kuen kao won the nobel prize in physics in 2009 for groundbreaking work on fiber-optic cables, which use thin threads of glass or plastic to carry information in the form of light.

Explanation:

To solve this, we identify adjectives (words describing nouns) and exclude articles. "Groundbreaking" describes "work", "thin" describes "threads", "fiber - optic" describes "cables". Articles like "the", "a", "an" are excluded.

Answer:

groundbreaking, thin, fiber - optic