You can't get a high score in the IELTS reading test without learning a lot of vocabulary.
For example, here are some words and phrases that my students needed to know for a reading test that we did:
- remained = stayed
- took a long time = slow
- of varying (size, price etc) = of different (size, price)
- virtually any = almost any
- non-stop = continuous
- unblemished = perfect, without a mark or scratch
- molten (glass or metal) = in liquid form due to heat
- instant commercial success = made a profit straight away
- flaws = faults, mistakes, weaknesses
- detecting = locating, finding, discovering
Write the new words and phrases that you read or hear in a notebook - that's the best way to improve your vocabulary knowledge.